ELECTRICALLY OPERATED AEROSOL GENERATING DEVICE WITH MEANS FOR DETECTING AN AIRFLOW IN THE DEVICE

Abstract

The present invention relates to an electrically operated aerosol generating device for generating an aerosol. The device comprises an air path extending through the device and configured to support airflow within it. The device further comprises a sound-generating member arranged in fluid communication with the air path and configured to generate sound caused by airflow passing the sound-generating member during use of the device when a user takes a puff. The device further comprises a puff detector comprising a vibration sensor. The vibration sensor is fluidly separated from the air path and configured to detect sound propagating from the sound-generating member to the vibration sensor.The invention further relates to an aerosol generating system comprising such a device and an aerosol generating article comprising the aerosol forming substrate.

Description

Electrically operated aerosol generating device with means for detecting an airflow in the device The present invention relates to an electrically operated aerosol generating device for generating an aerosol, particularly for generating an aerosol by releasing a substance from an aerosol-forming substrate into an airflow, wherein the device comprises means for detecting an airflow within the device. The invention further relates to an aerosol generating system comprising such a device and an aerosol generating article comprising the aerosol-forming substrate. Electrically operated aerosol generating devices used to generate inhalable aerosols by releasing a substance from an aerosol-forming substrate into an airflow are generally known from the prior art. For example, such devices may comprise an electric heater for heating an aerosol-forming substrate that is capable of releasing volatile compounds that form an inhalable aerosol when heated. As another example, such devices may comprise an atomizer for dispersing particles or droplets of an aerosol-forming substrate into an airflow so that they form an inhalable aerosol. To maintain a consistent user experience, the release of the substance from the aerosol-forming substrate must be kept at a certain level when a user takes a puff. However, the release of the substance can vary during consumption, particularly due to the airflow drawn through the system during the user's puff. For this reason, accurate puff detection is important for precise control of substance release. Puff detection can be achieved, for example, by measuring a pressure drop in the airflow through the device when a user takes a puff. To this end, many devices incorporate a pressure sensor in direct fluid communication with the airflow path through the device to directly detect an airflow indicating that a user is taking a puff. However, in such an arrangement, the sensor is directly exposed to conditions in the air path, for example, the effects of heat and humidity from aerosol formation. Because of this, proper airflow detection can be negatively affected, potentially leading to faulty or even non-functional puff detection. Therefore, it would be desirable to provide an electrically operated aerosol generating device comprising means for detecting puffs, utilizing the advantages of prior art solutions while mitigating their limitations. In particular, it would be desirable to have an electrically operated aerosol generating device comprising improved means for detecting an airflow through the device that is indicative of a user's puff. According to the present invention, an electrically operated aerosol generating device is provided for generating an aerosol, in particular an electrically operated aerosol generating device for generating an aerosol by releasing a substance from an aerosol-forming substrate into an airflow. The device comprises an air path extending through the device and configured to support an airflow within the device. The device further comprises a sound-generating member arranged in fluid communication with the air path and configured to generate sound caused by an airflow passing the sound-generating member during use of the device when a user takes a puff. Additionally, the device comprises a puff detector comprising a vibration sensor.The vibration sensor is fluidly separated, at least within the device, from the air path and is configured to detect the propagation of sound from the sound-generating member to the vibration sensor. Consequently, detecting the sound propagating from the sound-generating member to the vibration sensor can allow for the detection of airflow through the device. QfrdAnn / zznz / E / YiAi is indicative of a user's puff. According to the invention, it has been recognized that airflow, particularly changes in airflow that indicate a user is taking a puff, can be reliably detected by using the airflow to generate air vibrations (sound) or vibrations of at least a portion of the device that propagate and can therefore be detected remotely by a vibration sensor. Because of the ability to remotely detect propagating vibrations, the vibration sensor can be fluidly separated from the airflow path within the device. Advantageously, this fluid separation of the vibration sensor makes airflow and puff detection less prone to errors and thus more reliable.Furthermore, it has been recognized that the use of a sound-generating member can act as an amplifier of airflow through the air path in the sense that it generates vibrations that are transmitted to the remote vibration sensor. As used here, the term “sound” or “propagating vibrations” basically refers to a mechanical acoustic wave that propagates through a gaseous, fluid, or solid medium, specifically air or the structural components (solid matter) of the aerosol-generating device. The term “acoustic wave” refers to a type of energy propagation through adiabatic compression and decompression of the medium (air or solid matter of the device, respectively). The terms “acoustic waves” or “sound” can refer to acoustic waves or sound perceptible / audible to a human being through their auditory perception, specifically through hearing. The frequencies that can be heard by humans are generally within a range between 20 Hertz (Hz) and 20,000 Hertz (Hz). Likewise, the terms “acoustic waves” or “sound” can refer to acoustic waves or sound in a frequency range beyond the spectrum audible to a human being, specifically in a frequency range above 20,000 Hertz (Hz) or in a frequency range below 20,000 Hertz (Hz). QfrdAnn / zznz / E / YiAi Hertz (Hz). Consequently, the terms “acoustic waves” or “sound” can also be related to ultrasonic waves or sound, or to infrasonic waves or sound. In general, a sound-generating member can be any mechanical member suitable for generating sound by means of an airflow passing through the vibrating member. In this sense, a sound-generating member can also be referred to as an airflow-driven sound-generating member. To generate sound, the sound-generating member may comprise a sound-generating displacement structure configured to partially displace the airflow as it passes through the structure. Similar to displacement aerophones such as tubes, whistles, and flutes, an airflow passing through the sound-generating displacement structure is divided and modified by the structure, generating vibrations in the airflow—that is, adiabatic compressions and decompressions. Typically, the sound-generating displacement structure may comprise one or more edges, particularly sharp edges where the airflow meets as it passes through the structure. Preferably, the sound-generating displacement structure comprises at least one of the following: one or more slots, one or more ridges, one or more dimples, or one or more protrusions. When air passes along one or more slots, dimples, protrusions, or ridges, respectively, a laminar airflow coming into contact with the one or more slots, dimples, protrusions, or ridges is transformed into turbulent airflow due to collisions with the one or more slots or ridges, respectively. Consequently, some of the kinetic energy of the airflow, i.e., the dynamic pressure, is transformed into static pressure. If the sound-generating displacement structure comprises a plurality of slots or ridges, respectively, the partial displacement of the airflow creates a plurality QfrdAnn / zznz / E / YiAi Depending on the frequency of the sound to be generated, the periodic pattern can have a periodicity ranging from 0.5 ridges or slots per millimeter to 10 ridges or slots per millimeter, specifically from 1 ridge or slot per millimeter to 5 ridges or slots per millimeter, and preferably from 2 ridges or slots per millimeter to 4 ridges or slots per millimeter. That is, the periodic pattern can have a period length ranging from 0.1 millimeters to 2 millimeters, specifically from 0.2 millimeters to 1 millimeter, and preferably from 0.25 millimeters to 0.5 millimeters. Consequently, the generating displacement structure can comprise a plurality of ridges or slots, or both, with a distance between each pair of adjacent ridges or slots ranging from 0.1 millimeters to 2 millimeters, specifically from 0.2 millimeters to 1 millimeter, and preferably from 0.25 millimeters to 0.5 millimeters. For example, if the periodic pattern of the sound-generating displacement structure has a period length of 0.25 mm and the airflow speed passing the sound-generating displacement structure is 10 meters per second, a sound can be generated that has a frequency of approximately 40 kilo-Hertz (kHz). The periodic pattern can be a linear periodic pattern. The periodic pattern can be one-dimensional, such as an arrangement of a plurality of parallel grooves or ridges. That is, the pattern comprises periodicity along a single direction. The periodic pattern can also be a multidimensional pattern, specifically two-dimensional. That is, the pattern comprises periodicity along more than one direction, specifically two directions. For example, the pattern may comprise a first periodicity along a first direction and a second periodicity along a second direction. The first and second directions may be transverse, specifically perpendicular to each other.By way of example, the periodic pattern may comprise a first arrangement of a plurality of first parallel grooves or first ridges having a first periodicity along a first direction, and a second arrangement of a plurality of second grooves or second ridges. QfrdAnn / zznz / E / YiAi are parallel lines that have a second periodicity along a second direction. In particular, such a periodic pattern can be a cross pattern or a grid pattern. The periodic pattern may be a nonlinear periodic pattern. For example, the periodic pattern may comprise a plurality of curved grooves, particularly ring-shaped, or curved ridges, particularly ring-shaped. The periodic pattern may comprise a concentric ring pattern formed by a plurality of ring-shaped grooves or a plurality of ring-shaped ridges. The ring pattern or ring shape may be circular, elliptical, oval, rectangular, quadratic, or polygonal. With regard to symmetry, a periodic ring pattern may be advantageous with respect to an arrangement of the sound-generating displacement structure on a distal end surface of a cylindrical receiving cavity. As another example, the periodic pattern may comprise a spiral pattern formed by a spiral-shaped groove or ridge. As another example, the periodic pattern may comprise a honeycomb pattern comprising a plurality of grooves or ridges forming the outline of the honeycomb pattern. To improve sound generation, a longitudinal extension of at least one or more grooves or one or more ridges may be transverse, in particular perpendicular to a direction of airflow passing the sound-generating member during use of the device. At least one of the ridge heights or groove depths varies, and may be constant along the sound-generating displacement structure in the direction of airflow passing the sound-generating member during device use. Alternatively, at least one of the ridge heights or groove depths varies, and may include increases along the sound-generating displacement structure in the direction of airflow passing the sound-generating member during device use. This may allow the sound generation to be tailored to the geometry and dimensions of the air path, for example, to provide a specific resistance to extraction (RTD). QfrQAnn / ZZnZ / B / YIAI Preferably, the sound-generating member, in particular the sound-generating displacement structure, is part of a wall member that defines at least a portion of the air path through the device. Advantageously, this can simplify the manufacturing and assembly of the device. In particular, having the sound-generating displacement structure integrated with a wall member of the device allows for a compact device design. For example, the sound-generating displacement structure may comprise one or more slots, or one or more ridges, or one or more slots and one or more ridges formed in a wall member of the device that defines at least a portion of the air path through the device. Similarly, the sound-generating member, in particular the sound-generating displacement structure, may be a separate element or member, separate from, in particular attached to, a wall member that defines at least a portion of the air path through the device. The sound-generating displacement structure is preferably a rigid structure. As such, neither the sound-generating displacement structure as a whole nor any structural component of the sound-generating displacement structure experiences deflection at the center of mass. However, this does not preclude sound from propagating through the sound-generating displacement structure. Alternatively or in addition to a sound-generating displacement structure, the sound-generating member may comprise at least one airflow-driven vibrating element for periodically interrupting the airflow passing the vibrating element. As in interruption aerophones, particularly reed aerophones such as oboes or clarinets, an airflow is directed against a flexible vibrating element, such as a single reed or a pair of reeds, causing the vibrating element to vibrate. Due to the airflow-driven vibrations of the flexible vibrating element, the airflow The flow of air passing through the vibrating element is periodically interrupted, causing the air to move, which produces sound. Accordingly, the at least one vibrating element may comprise a lamella or a plate or a pair of plates or a pair of lamellae. Similarly, the at least one vibrating element may comprise a restricted movable element designed to periodically interrupt the airflow passing through the vibrating element. To restrict its free movement, the movable element may be enclosed in a cage, such as a ball in a ball whistle. Alternatively, the movable element may be restricted by coupling it to one end of a spring element, the other end of which is fixedly coupled to the device. Of course, the sound-generating member may comprise a plurality of vibrating elements, for example, a plurality of lamellae or plates. Having a plurality of vibrating elements advantageously enhances the amplitude of the generated sound, which, in turn, promotes the propagation of the sound toward the vibration sensor. As mentioned previously, the amplitude and frequency / frequency spectrum of the generated sound can be affected by the dimensions and configuration of the air path and the sound-generating member. To make the generated sound imperceptible to the device user, particularly to avoid unwanted noise exposure, the generated sound is preferably outside the frequency spectrum audible to humans, and even more preferably outside the frequency spectrum audible to many animals, particularly pets such as dogs or cats. Consequently, the air path and the sound-generating member can be configured so that the sound generated during device use is in a frequency range above 15 kilohertz (kHz), preferably above 20 kilohertz (kHz), with the strongest preference being above 20 kilohertz (kHz). QfrdAnn / zznz / E / YiAi To keep the vibration sensor fluidly separated—at least within the device from the air path through the device—the vibration sensor can be arranged in a compartment of the device that is fluidly separated—at least within the device—from the air path through the device. Because of this, the vibration sensor is not in direct fluid communication with the air path, and in particular, it is not in direct contact with any fluid (air, aerosol, aerosol particles) passing through the air path.This does not preclude the vibration sensor from being in indirect fluid communication with the air path through the device, for example, through direct fluid communication with the ambient air surrounding the device, which in turn may be in direct fluid communication with the air path through the device, for example, through an air inlet or outlet. In this configuration, the vibration sensor is still sufficiently isolated from any fluid (air, aerosol, aerosol particles) passing through the air path. Consequently, the device compartment that fluidly separates from the air path may be in fluid communication with the device environment, particularly with the ambient air surrounding the device. Alternatively, the device compartment, which is fluidly separated from the air path through the device, can also be fluidly sealed from the device environment, particularly from the ambient air surrounding the device. Although the vibration sensor is fluidly separated from the air path through the device, the sound generated in the sound-generating member can easily propagate from the sound-generating member to the vibration sensor through various mediums. Specifically, the sound can propagate through the air inside the device, through the ambient air surrounding the device, and through solid material within the device, such as a wall member—for example, a wall member that defines at least a portion of the air path or a wall member that separates the aforementioned compartment. QfrdAnn / zznz / E / YiAi above the air path. Depending on the sound propagation properties of the different media and depending on the physical structure and dimensions of the device, sound can propagate from the sound-generating member directly to the vibration sensor. Alternatively or additionally, sound can propagate from the sound-generating member to the vibration sensor through the device's environment. That is, sound can escape at least partially from the device and re-enter the device before reaching the vibration sensor. The vibration sensor can be arranged within the device such that sound transmission to the vibration sensor occurs through the air surrounding at least a portion of the sensor. Therefore, the vibration sensor can be arranged within the device so that it is at least partially surrounded by a fluid, particularly air. Similarly, the vibration sensor can be arranged within the device such that sound transmission to the vibration sensor occurs from the solid material of a device component with which the vibration sensor is in contact. For example, the vibration sensor can be arranged in a wall member of the device, such as a wall member that fluidly separates the sensor from the air path. In particular, the vibration sensor can be arranged on one side of a wall member opposite a side of the wall member that defines at least a portion of the air path through the device. The vibration sensor may include an electroacoustic transducer. An electroacoustic transducer is a device designed to convert acoustic energy into electrical energy. Depending on the nature of the sound transmission in the vibration sensor, the sensor may include, for example, a microphone, an accelerometer, a strain gauge, a piezoelectric acoustic transducer, or a magnetic acoustic transducer. A piezoelectric acoustic transducer is a device that uses the piezoelectric effect to detect sound by measuring changes in pressure, acceleration, strain, or force. QfrdAnn / zznz / E / YiAi caused by sound and by converting the measured change into an electrical signal. Similarly, an acoustic magnetic transducer is a device that uses electromagnetic induction to detect sound by measuring changes in pressure, acceleration, strain, or force caused by sound and converting the measured change into an electrical signal. Similarly, accelerometers or strain gauges can be used to measure the motion and vibration of a structure exposed to dynamic loading caused by sound coupling in these types of sensors. A strain gauge is a sensor whose resistance varies with the applied force. It converts force, pressure, or strain into a change in electrical resistance that can be measured. An accelerometer measures the acceleration of a sensing mass, such as a membrane, that responds to oscillations in air pressure or vibrations / sounds in a solid body to which the sensing mass is mechanically coupled. The microphone can be an electromagnetic microphone (also known as a dynamic or moving-coil microphone) that uses electromagnetic induction to convert acoustic energy into electrical energy. Electromagnetic microphones are robust, relatively inexpensive, and resistant to moisture. Electromagnetic microphones use the same dynamic principle as a loudspeaker, only in reverse. A small, movable induction coil, located in the magnetic field of a permanent magnet, is coupled to the diaphragm. When sound enters the microphone, the sound wave moves the diaphragm. As the diaphragm vibrates, the coil moves within the magnetic field, producing a variable current in the coil through electromagnetic induction. This type of microphone can also be referred to as a magnetic acoustic transducer or be a specific example of a magnetic acoustic transducer. The microphone can be an electrostatic microphone, such as a condenser microphone, an electret microphone, or a piezoelectric microphone. The latter can also be referred to as a piezoelectric acoustic transducer or can be a specific example of a piezoelectric acoustic transducer, the details of which are described below. QfrdAnn / zznz / E / YiAi The microphone can be a fiber optic microphone. A fiber optic microphone converts acoustic waves into electrical signals by detecting changes in the intensity of light passing through an optical fiber. During operation, light from a laser source travels through an optical fiber to illuminate the surface of a reflective diaphragm. The diaphragm's sound vibrations modulate the intensity of the light reflected off the diaphragm in a specific direction. The modulated light is transmitted through a second optical fiber to a photodetector, which transforms the intensity-modulated light into an electrical signal. Fiber optic microphones have a high frequency and dynamic range. Advantageously, fiber optic microphones are not affected by electric, magnetic, or electrostatic fields.Therefore, fiber optic microphones are ideal for use in electrically operated aerosol generating devices, particularly with regard to the inductive heating of aerosol generating devices. The device may comprise a device housing that includes the air path through the device. The device housing may be configured to receive the aerosol-forming substrate that includes the substance to be discharged into the airflow through the air path. In general, the aerosol generating device may comprise at least one air inlet where air can enter the air path through the device. As such, the air inlet can be considered a starting point of the air path through the device. Similarly, the aerosol generating device may comprise at least one air outlet where air can exit the air path through the device. As such, the air outlet can be considered an end point of the air path through the device. The air outlet may be provided, for example, in a nozzle portion of the QfrdAnn / zznz / E / YiAi device. The aerosol generating device may comprise a receiving cavity for detachably receiving the aerosol forming substrate or at least a portion of an aerosol generating article comprising the substrate. The receiving cavity may include an insertion opening through which an aerosol-forming substrate or aerosol-generating article can be inserted into the receiving cavity. As used herein, the direction in which the aerosol-forming substrate or aerosol-generating article is inserted is referred to as the insertion direction. Preferably, the insertion direction corresponds to the extent of a longitudinal axis, in particular a central axis of the receiving cavity. After insertion into the receiving cavity, at least a portion of the aerosol-generating article may still extend outward through the insertion opening. The outward-extending portion is preferably intended for interaction with a user, particularly for bringing it to the user's mouth. Therefore, during use of the device, the insertion opening may be close to the user's mouth. Therefore, as used herein, sections near the insertion opening or near the user's mouth during use of the device, respectively, are generally designated with the prefix proximal. Sections located further away are generally designated with the prefix distal. With regard to this convention, the receiving cavity may be arranged or located in a proximal portion of the aerosol generating device. The insertion opening may be arranged or located at a proximal end of the aerosol generating device, particularly at a proximal end of the receiving cavity. The air path through the device may extend at least partially through a wall that defines at least a portion of the receiving cavity. Such configurations are described, for example, in WO 2013 / 102609 A2. QfrdAnn / zznz / E / YiAi Additionally or alternatively, the air path through the device may extend at least partially along an internal surface of the receiving cavity. For this purpose, the receiving cavity may comprise a plurality of protrusions extending into the interior of the receiving cavity. Preferably, the plurality of protrusions are spaced apart from each other so that an air path, or at least a portion of an air path, is formed through the device between neighboring protrusions, i.e., through the gaps (free space) between neighboring protrusions. Furthermore, the plurality of protrusions may be configured to come into contact with at least a portion of the aerosol-forming substrate or aerosol-generating article to retain the substrate or aerosol-generating article within the receiving cavity. Examples of such a configuration are described in WO 2018 / 050735 A1. With respect to this configuration, an air inlet of the device is preferably located at an insertion opening in the receiving cavity used to insert the substrate or article into the cavity. When the substrate or article is received into the cavity, air can be drawn into the receiving cavity at the edge of the insertion opening and further along the portion of the air path formed between the inner surface of the receiving cavity and the outer circumference of the aerosol-forming substrate or aerosol-generating article. Preferably, a portion of the air path extends through the aerosol-forming substrate or article. From there, the air path can pass directly to a user's mouth. Alternatively, the air path can extend through a nozzle portion of the device, exiting the device through an air outlet in the nozzle portion. The aerosol-generating device may comprise one or more end stops arranged within the receiving cavity, particularly at a distal end of the receiving cavity. The one or more end stops are preferably configured to limit the insertion depth of the aerosol-forming substrate or the aerosol-generating article into the receiving cavity. In particular, the one or more end stops may be configured to prevent the aerosol-forming substrate from QfrdAnn / zznz / E / YiAi The aerosol or aerosol-generating article abuts a distal end surface of the receiving cavity that is opposite an insertion opening of the receiving cavity at a proximal end of the receiving cavity. Therefore, one or more end stops advantageously provide clearance within a distal portion of the receiving cavity, allowing free airflow between a distal end of the receiving cavity and a distal end of an aerosol-generating article when the substrate or article is received into the receiving cavity. The one or more end stops may comprise a contact surface that an aerosol-generating article, particularly a distal end of an aerosol-generating article, can abut when the article is received into the receiving cavity. Preferably, the aerosol generating device may comprise a plurality of separate end stops, for example three end stops, arranged within the receiving cavity, particularly at a distal end of the receiving cavity. The multiple end stops can be arranged symmetrically around a longitudinal axis, particularly a central axis of the receiving cavity. Preferably, the plurality of end stops can be equally spaced around the longitudinal axis, particularly the central axis of the receiving cavity. As described above, this allows free airflow around the end stops and a received item in the receiving cavity. In general, the receiving cavity can have any suitable shape. In particular, the shape of the receiving cavity can correspond to the shape of the aerosol-forming substrate or the aerosol-generating article to be received within it. Preferably, the receiving cavity can have an essentially cylindrical or tapered shape, for example, an essentially conical or essentially truncated conical shape. Furthermore, the receiving cavity can have any suitable cross-section as seen in a plane perpendicular to a longitudinal axis of the receiving cavity or perpendicular to an insertion direction of the article. In particular, the cross-section of the receiving cavity can correspond to the shape of the aerosol-generating article to be received. QfrdAnn / zznz / E / YiAi ella. The receiving cavity preferably has an essentially circular cross-section. Alternatively, the receiving cavity may have an essentially elliptical cross-section, an essentially oval cross-section, an essentially square cross-section, an essentially rectangular cross-section, an essentially triangular cross-section, or an essentially polygonal cross-section. As used herein, the shapes and cross-sections mentioned above preferably refer to a shape or cross-section of the receiving cavity without regard to any protrusions. The receiving cavity can be formed as a receiving cavity module, in particular as a tubular sleeve, which can be inserted into a main body of the aerosol generating device. Advantageously, this allows for a modular unit of the aerosol generating device. Alternatively, at least part of the receiving cavity can be integrally formed with the main body. By providing at least part of the receiving cavity as part of the main body, the number of parts that the aerosol-generating device needs to assemble can be reduced. The sound-generating member may be located in a distal end portion of the receiving cavity, particularly on a distal end surface of the receiving cavity. The distal end surface of the receiving cavity may be formed by a wall member that separates the receiving cavity from other portions of the device, particularly a portion of the device comprising the vibration sensor and / or the electronic components (electrical circuit, controller, power supply). Preferably, the vibration sensor is arranged on one side of such a wall member opposite the side of the wall member that defines the distal end surface of the receiving cavity. In addition to the vibration sensor, the puff detector may also include a QfrdAnn / zznz / E / YiAi electrical circuit for converting the output signal of the vibration sensor into a signal that indicates a sound. The electrical circuit may comprise at least one of a transimpedance amplifier for current-to-voltage conversion, an inverting signal amplifier, a single-ended to differential converter, an analog-to-digital converter, and a microcontroller. The puff detector or electrical circuit may also include one or more electronic filters to filter the output signal from the vibration sensor. Advantageously, the filtering can reduce different types of noise, particularly parasitic noise detected by the vibration sensor. In general, aerosol generation, in particular the release of substance from the aerosol-forming substrate into the airflow through the device, can be carried out in different ways, as described above. For example, the device may include an atomizer for dispersing particles or droplets of an aerosol-forming substrate into an airflow so that they form an inhalable aerosol. The atomizer may be an ultrasonic atomizer. Alternatively, the aerosol generating device may comprise an electric heater for heating an aerosol-forming substrate that is capable of releasing volatile compounds that form an inhalable aerosol when heated and released into an airflow. The electric heater of the aerosol-generating device can be configured as an inductive heater. The inductive heater can comprise an induction source including an inductor configured to generate an alternating electromagnetic field, particularly a high-frequency field, within the device, specifically within a receiving cavity of the device as described above. The alternating electromagnetic field, particularly the high-frequency field, can be in the range of 500 kHz (kilohertz) to 30 MHz (megahertz), specifically between 5 MHz and 15 MHz, preferably between 5 MHz and 10 MHz. The alternating electromagnetic field is used to inductively heat a susceptor that is in thermal contact with or near the aerosol-forming substrate to be heated. The inductor can QfrdAnn / zznz / E / YiAi be arranged so as to surround the susceptor and at least a portion of the aerosol-forming substrate during use of the device. For example, the inductor may be an inductor coil, e.g., a helical coil arranged within a side wall of the receiving cavity. For example, the inductor may be arranged so as to surround at least a portion of the receiving cavity. Alternatively, the heater may be a resistive heater comprising a resistive heating element. The resistive heating element is configured to heat up when an electric current passes through it due to its improper ohm resistance or resistive load. For example, the resistive heating element may comprise at least one resistive heating wire, resistive heating track, resistive heating grid, or resistive heating mesh. During use of the device, the resistive heating element is in thermal contact with or near an aerosol-forming substrate to be heated. The aerosol generating device may further comprise a controller operatively coupled with the puff detector to determine a user's puff based on signals provided by the vibration sensor, in particular based on a signal provided by the puff detector that is indicative of airflow through the device's air path. The controller can also be configured to control the overall operation of the aerosol generating device, particularly the heating process. Based on the airflow indicator signal, the controller can be configured to control the release of the substance from the aerosol-forming substrate into the airflow. For example, if the aerosol generating device includes an electric heater for heating the aerosol-forming substrate, the controller can be operatively coupled to the heater and configured to control the heating process to maintain the temperature of QfrdAnn / zznz / E / YiAi heating to a certain level when a user takes a puff. The controller and at least parts of the puff detector may be an integral part of an overall electrical circuit of the aerosol generating device. The aerosol-generating device may include a power supply, preferably a battery such as a lithium iron phosphate battery. Alternatively, the power supply may be another form of charge storage device, such as a capacitor. The power supply may require recharging and may have a capacity that allows sufficient energy storage for one or more user experiences. For example, the power supply may have sufficient capacity to allow continuous aerosol generation for a period of approximately six minutes or for a period that is a multiple of six minutes. In another example, the power supply may have sufficient capacity to allow a predetermined number of puffs or discrete activations of the heating device. The present invention further relates to an aerosol generating system comprising an aerosol generating device according to the invention and as described herein. The system further comprises an aerosol generating article including at least one aerosol-forming substrate to be heated by the device, wherein at least a portion of the article can be or is detachably received in the receiving cavity of the device. The aerosol-generating article may be a consumable, particularly one intended for single use. The aerosol-generating article may be a tobacco product. In particular, the article may be a bar-shaped article, preferably a cylindrical bar-shaped article, which may resemble conventional cigarettes. QfrdAnn / zznz / E / YiAi The article may comprise one or more of the following elements: a filter element, a cooling element, a substrate element, and an optional second support element. Preferably, the aerosol-generating article comprises at least a first support element, a second support element, and a substrate element located between the first support element and the second support element. All the aforementioned elements can be arranged sequentially along a longitudinal axis of the article in the order described above, where the first support element is preferably located at a distal end of the article and the filter element is preferably located at a proximal end. Each of the aforementioned elements can be essentially cylindrical. In particular, all elements can have the same external cross-sectional shape. Furthermore, the elements can be enclosed by an outer casing that holds the elements together and maintains the article's convenient cross-sectional shape. Preferably, the casing is made of paper. In the case of an inductively heated aerosol generating system, the article may further comprise a susceptor. The susceptor is positioned in thermal proximity or in thermal contact with the aerosol forming substrate so that, during use, the susceptor can be inductively heated by the inductive heating arrangement when the article is received into the device cavity. For example, the susceptor may be a susceptor strip, a susceptor blade, a susceptor tube, or a susceptor sleeve. The susceptor may be part of the substrate element. As used herein, the term susceptor refers to an element capable of converting electromagnetic energy into heat when subjected to an alternating magnetic field. This may result from hysteresis losses and / or eddy currents induced in the susceptor, depending on the electrical and magnetic properties of the susceptor material.Hysteresis losses occur in ferromagnetic or ferrimagnetic susceptors due to magnetic domains within the material that switch under the influence of an alternating electromagnetic field. Eddy currents can be induced if the susceptor is electrically conductive. In the case of a ferromagnetic or ferrimagnetic susceptor... QfrdAnn / zznz / E / YiAi electrically conductive ferrimagnetic, heat can be generated due to both eddy currents and hysteresis losses. At least one of the first support element and the second support element may comprise a central air passage. Preferably, at least one of the first support element and the second support element may comprise a hollow cellulose acetate tube. Alternatively, the first support element may be used to cover and protect the distal front end of the substrate element. The aerosol cooling element is an element with a large surface area and low suction resistance, for example, 15 mmWG to 20 mmWG. During use, an aerosol formed by volatile compounds released from the substrate element is drawn through the aerosol cooling element, allowing the aerosol to form and cool before being conveyed to the proximal end of the aerosol-generating article. The filter element preferably serves as a nozzle, or as part of a nozzle in conjunction with the aerosol cooling element. As used herein, the term “nozzle” refers to a portion of the article through which the aerosol exits the aerosol-generating article. Similarly, the aerosol-generating article can be a capsule containing an aerosol-forming powder (as an aerosol-forming substrate) that is dispersed in an airflow to generate an aerosol. Other features and advantages of the aerosol generating system and the aerosol generating article according to the present invention have already been described above with respect to the aerosol generating device and apply equally. As used herein, the expression “aerosol-forming substrate” refers to a substrate capable of releasing volatile compounds that can form an aerosol. In particular, the aerosol-forming substrate can be a substrate capable of releasing volatile compounds that can form an aerosol. Such an aerosol-forming substrate is QfrdAnn / zznz / E / YiAi intended to be heated rather than burned in order to release volatile aerosol-forming compounds. The aerosol-forming substrate may be a solid aerosol-forming substrate, a liquid aerosol-forming substrate, a gel-type aerosol-forming substrate, or any combination thereof. That is, the aerosol-forming substrate may comprise, for example, both solid and liquid components. The aerosol-forming substrate may comprise a tobacco-containing material containing volatile tobacco flavor compounds, which are released from the substrate upon heating. Alternatively or additionally, the aerosol-forming substrate may comprise a non-tobacco material. The aerosol-forming substrate may further comprise an aerosol former. Examples of suitable aerosol formers are glycerin and propylene glycol.The aerosol-forming substrate may also include other additives and ingredients, such as nicotine or flavorings. The aerosol-forming substrate may also be a paste-like material, a pouch of porous material comprising an aerosol-forming substrate, or, for example, loose tobacco mixed with a gelling or adhesive agent, which could include a common aerosol former such as glycerin, and which is compressed or molded into a cap. Similarly, the aerosol-forming substrate may be an aerosol-forming powder. The aerosol-forming powder may comprise a nicotine powder. The term “nicotine” refers to nicotine and nicotine derivatives such as nicotine salts. Accordingly, the nicotine powder may be a nicotine salt or a nicotine salt hydrate. Suitable nicotine salts or nicotine salt hydrates include, for example, nicotine tartrate, nicotine aspartate, nicotine lactate, nicotine glutamate, nicotine bitartrate, nicotine salicylate, nicotine fumarate, nicotine monopyruvate, or nicotine hydrochloride, and combinations thereof. Nicotine powder may have any particle size distribution suitable for pulmonary delivery of nicotine to a user. In particular, at least approximately 90 percent by weight (wt%) of the nicotine powder may have a particle size of approximately 10 micrometers or less, preferably approximately 7 micrometers or less. The nicotine powder preferably has an average diameter ranging from approximately 0.1 to approximately 10 micrometers, with a greater preference for approximately 1 to approximately 7 micrometers, particularly with a greater preference for approximately 2 to approximately 6 micrometers. Nicotine powder particles can have a modified surface; for example, nicotine salt particles can be coated. A preferred coating material is leucine. Particularly suitable nicotine powder particles include L-leucine-coated nicotine bitartrate, L-leucine-coated nicotine glutamate, and L-leucine-coated aspartate. The capsule preferably contains between approximately 5 and approximately 20 milligrams of nicotine powder, in particular approximately 10 milligrams of nicotine powder. Preferably, the capsule contains enough nicotine powder to supply between approximately 10 and approximately 30 puffs to a user. The nicotine powder described herein is preferably carrier-free. Being carrier-free allows the nicotine powder to be inhaled and delivered to the user's lungs at airflow or inhalation velocities similar to those typically encountered during smoking. Furthermore, because the nicotine powder is carrier-free, the inhaler's airflow path can have a simple geometry or configuration. However, aerosol-forming powder may also contain carrier particles that serve to increase the fluidization of the active particles and to improve dose uniformity by acting as a diluent or thickening agent in a formulation. QfrdAnn / zznz / E / YiAi As an alternative or in addition to nicotine powder, aerosol-forming powder may also comprise another active ingredient or agent, such as an active pharmaceutical ingredient. This active ingredient or agent may be mixed into the same capsule. The second active ingredient or agent may have a similar average diameter size range to the nicotine powder described above. The following is a non-exhaustive list of non-limiting examples. Any or more of the features in these examples may be combined with any one or more features of another example, modality, or aspect described herein. Example Ex1: An electrically operated aerosol generating device for generating an inhalable aerosol by releasing an aerosol-forming substrate into an airflow, the device comprising: an air path that extends through the device and is configured to support airflow into the device; a sound-generating member disposed in fluid communication with the air path and configured to generate sound caused by an airflow passing the sound-generating member during use of the device when a user takes a puff; and a puff detector comprising a vibration sensor, wherein the vibration sensor is fluidly separated from the air path and configured to detect sound propagating from the sound-generating member to the vibration sensor, thereby enabling the detection of an airflow through the device that is indicative of a user taking a puff. Example Ex2: The aerosol generating device according to Example Ex 1, wherein the sound generating member comprises a sound generating displacement structure for at least partially displacing the airflow when passing the sound generating displacement structure. Example Ex3: The aerosol generating device according to Example Ej2, wherein the sound-generating displacement structure comprises at least one of: one or more grooves or one or more ridges, one or more dimples, or one or more protrusions. QfrdAnn / zznz / E / YiAi Example Ex4: The aerosol generating device according to Example Ex3, wherein a longitudinal extension of one or more grooves, or a longitudinal extension of one or more ridges, or a longitudinal extension of one or more grooves and a longitudinal extension of one or more ridges is transverse, in particular perpendicular to a direction of airflow passing the sound generating member during use of the device. Example Ex5: The aerosol generating device in accordance with any one of Examples Ej3 to Ej4, wherein the one or more slots, or the one or more ridges, or the one or more slots and the one or more ridges comprise a triangular shape, a sinusoidal shape, or a rectangular shape. Example Ex6: The aerosol generating device in accordance with any one of Examples Ej3 to Ej5, wherein at least one of a ridge height or a groove depth varies, in particular increases along the sound-generating displacement structure in a direction of airflow passing the sound-generating member during use of the device. Example Ex7: The aerosol generating device in accordance with any example Ej3 to Ej6 wherein the plurality of grooves, ridges, dimples or protrusions is distributed uniformly or unevenly along the air passage. Example Ex8: The aerosol generating device in accordance with any example Ej1 to Ej7, wherein the sound generating member, in particular the sound generating displacement structure, is part of or integrated into a wall member that defines at least a portion of the air path through the device. Example Ex9: The aerosol generating device according to any example Ej2 to Ej8, wherein the sound-generating displacement structure comprises a periodic pattern. QfrdAnn / zznz / E / YiAi Example Ex10: The aerosol generating device according to Example Ej9, wherein the periodic pattern has a period length in the range of 0.1 millimeters to 2 millimeters, in particular between 0.2 millimeters and 1 millimeter, preferably between 0.25 millimeters and 0.5 millimeters. Example Ex11: The aerosol generating device in accordance with any one of Examples Ej8 to Ej10, wherein the periodic pattern is either a linear periodic pattern or a non-linear periodic pattern. Example Ex12: The aerosol generating device in accordance with any one of Examples Ej8 to Ej11, wherein the periodic pattern is a one-dimensional periodic pattern, in particular an arrangement of a plurality of parallel grooves or ridges. Example Ex13: The aerosol generating device according to any one of Examples Ej8 to Ej 11, wherein the periodic pattern comprises a first set of a plurality of first parallel grooves or first ridges having a first periodicity along a first direction, and a second set of a plurality of second parallel grooves or second ridges having a second periodicity along a second direction. Example Ex14: The aerosol generating device in accordance with Example Ex 13, wherein the first direction and the second direction are transverse, in particular perpendicular to each other. Example Ex15: The aerosol generating device in accordance with any one of Examples Ej8 to Ej10, wherein the periodic pattern comprises at least one or more curved grooves, in particular ring-shaped, or one or more curved ridges, in particular ring-shaped. Example Ex16: The aerosol generating device according to any one of Examples Ex8 to Ex10, wherein the periodic pattern comprises a concentric ring pattern formed by a plurality of ring-shaped grooves or a plurality of ring-shaped ridges QfrdAnn / zznz / E / YiAi ring Example Ex17: The aerosol generating device in accordance with any one of Examples Ej8 to Ej10, wherein the periodic pattern comprises a spiral pattern formed by a spiral-shaped groove or ridge. Example Ex18: The aerosol generating device in accordance with any one of Examples Ej3 to Ej10, wherein the periodic pattern may comprise a honeycomb pattern comprising a plurality of grooves or ridges forming the outline of the honeycomb pattern. Example Ex19: The aerosol generating device in accordance with any one of Examples Ej2 to Ej 18, wherein the sound-generating displacement structure is a rigid structure. Example Ex20: The aerosol generating device in accordance with any one of the preceding examples, wherein the sound-generating member, in particular the sound-generating displacement structure, is a separate element or member, separate from, in particular attached to, a wall member that defines at least a portion of the air path through the device. Example Ex21: The aerosol generating device in accordance with any one of the preceding examples, wherein the sound generating member comprises at least one airflow-driven vibrating element configured to periodically interrupt an airflow passing through the vibrating element. Example Ex22: The aerosol generating device according to Example Ej21, wherein the at least one vibrating element comprises a sheet or a lamella or a pair of sheets or a pair of lamellae. Example Ex23: The aerosol generating device in accordance with any one of the above examples, wherein the air path and the sound generating member are configured so that the sound generated during use of the device is in a frequency range above 15 kilo-Hertz (kHz), preferably above 20 kilo-Hertz (kHz), more preferably above kilo-Hertz (kHz). QfrdAnn / zznz / E / YiAi Example Ex24: The aerosol generating device in accordance with any one of the above examples, wherein the vibration sensor is disposed in a compartment of the device that is fluidly separated from the air path through the device. Example Ex25: The aerosol generating device in accordance with Example Ex 24, wherein the device compartment, which is fluidly separated from the air path, is in fluid communication with the device environment. Example Ex26: The aerosol generating device in accordance with Example Ex 24, wherein the device compartment, which is fluidly separated from the air path, is fluidly sealed from the device environment, in particular from the ambient air surrounding the device. Example Ex27: The aerosol generating device in accordance with any one of the preceding examples, wherein the vibration sensor comprises a microphone, an accelerometer, an extensometer, or a piezoelectric transducer or an acoustic magnetic transducer. Example Ex28: The aerosol generating device in accordance with any one of the preceding examples, wherein the vibration sensor is disposed on one side of a wall member opposite one side of the wall member that defines at least a portion of the air path through the device. Example Ex29: The aerosol generating device in accordance with any one of the preceding examples, wherein the device comprises a receiving cavity for detachably receiving the aerosol forming substrate or at least a portion of an aerosol generating article comprising the substrate. Example Ex30: The aerosol generating device in accordance with Example Ej29, QfrdAnn / zznz / E / YiAi wherein the receiving cavity may comprise an insertion opening through which an aerosol-forming substrate or an aerosol-generating article may be inserted into the receiving cavity Example Ex31: The aerosol generating device in accordance with any one of Examples Ej29 to Ej30, wherein the air path extends at least partially along an internal surface of the receiving cavity and / or through a wall defining at least a portion of the receiving cavity. Example Ex32: The aerosol generating device in accordance with any one of Examples Ej29 to Ej31, wherein the sound generating member is located in a distal end portion of the receiving cavity, in particular on a distal end surface of the receiving cavity. Example Ex33: The aerosol generating device in accordance with any one of the preceding examples, wherein the puff detector comprises one or more electronic filters for filtering the output signal from the vibration sensor. Example Ex34: The aerosol generating device in accordance with any one of the preceding examples, further comprising an atomizer for dispersing particles or droplets of an aerosol-forming substrate into an airflow such as to form an inhalable aerosol. Example Ex35: The aerosol generating device in accordance with any one of Examples Ex 1 to Ex33, further comprising an electric heater for heating an aerosol forming substrate. Example Ex36: The aerosol generating device according to Example Ex35, wherein comprising an electric heater comprises an inductive heater or a resistive heater. Example Ex37: The aerosol generating device according to Example Ej35, wherein the inductive heater comprises an inductor, in particular an induction coil, for generating an alternating magnetic field within the device, in particular within a receiving cavity of the device. QfrdAnn / zznz / E / YiAi Example Ex38: An aerosol generating system comprising an aerosol generating device according to any one of the examples and an aerosol generating article comprising an aerosol forming substrate, wherein a portion of the article is detachably received or can be detachably received in the device, in particular in a receiving cavity of the device. Examples of the invention will be further described, with reference to the accompanying figures, in which: Figure 1 schematically illustrates a first illustrative embodiment of an aerosol generating device according to the present invention in a cross-sectional view; Figure 2 shows details of the aerosol generating device in accordance with Figure 1; Figure 3 shows additional details of the sound-generating member of the aerosol-generating device in accordance with Figure 1; Figure 4 shows details of the sound-generating member of the aerosol-generating device according to Figure 1; and Figure 5 schematically illustrates a second illustrative embodiment of an aerosol-generating device according to the present invention in a cross-sectional view. Figure 1 schematically illustrates a first embodiment of an aerosol generating system 1 according to the present invention. The system 1 comprises two main components: an electrically operated aerosol generating device 100 and an aerosol generating article 190 for use with the device 100. The device 100 is configured to heat an aerosol-forming substrate 191 contained within the article 190. The substrate 191 is capable of releasing volatile compounds that form an inhalable aerosol when heated and is released into an airflow passing through the system during use 1. QfrdAnn / zznz / E / YiAi The aerosol generating device 100 has an elongated shape and comprises a distal portion 101 and a proximal portion 102. Within the proximal portion 102 is the inductive heating device 100. The inductive heating device comprises an induction coil 140 for generating an alternating magnetic field, particularly of high frequency, within the receiving cavity 120. Preferably, the high-frequency magnetic field can be in the range between 500 kHz (kilohertz) and 30 MHz (megahertz), particularly between 5 MHz (megahertz) and 15 MHz (megahertz), preferably between 5 MHz (megahertz) and 10 MHz (megahertz). In the present embodiment, the induction coil 140 is a helical coil arranged within the housing of the device 110. The coil 140 circumferentially surrounds a portion of the cylindrical cavity 120 in coaxial alignment with the length axis of the receiving cavity 120.The alternating magnetic field is used to inductively heat a susceptor 141 disposed within the aerosol-forming substrate 191 of article 190 such as to experience the magnetic field generated by the induction coil 140 when article 190 is received in the cavity 120. In the present embodiment, the susceptor 140 is a susceptor blade disposed within the substrate element 192 along the longitudinal axis of article 190 such as to be in direct physical contact with the aerosol-forming substrate 191. Consequently, when the inductive heating device is activated, a high-frequency alternating current is passed through the induction coil 140, causing an alternating magnetic field to be generated within the cavity 120. Depending on the electrical and magnetic properties of the susceptor material, the alternating magnetic field induces at least one eddy current or hysteresis loss in the susceptor 141. As a result, the susceptor 141 heats up to a temperature sufficient to vaporize compounds from the aerosol-forming substrate 191. The vaporized compounds are released and carried in an airflow through article 190 from the substrate element 192 at the distal end of article 190, through the support element 193 and the cooling element 194, and into the filter element 195.Throughout this process, the vaporized substances cool to form an inhalable aerosol that can subsequently escape from the breath. QfrdAnn / zznz / E / YiAi article 190 through filter element 195 at the proximal end of article 190. According to the invention, the aerosol-generating device 100 comprises an air path 180 for providing airflow through the system 1 in which the aerosol-forming substrate substances can be released to form an inhalable aerosol. As indicated by the curved arrows 180 in Figure 1, the aerosol-generating article system 1 of the present embodiment comprises an air path that begins at an insertion opening 122 at the proximal end of the receiving cavity 120 and is used to insert the aerosol-generating article 190 into the cavity 120. As such, the insertion opening 122 also serves as an air inlet for the device 100. The air path 180 further extends along the inner surface of the receiving cavity 120 toward the surface of the distal (lower) end of the receiving cavity 120.The final portion of the air path is formed between the inner surface of the receiving cavity 120 and the outer circumference of the aerosol-generating article 190 as it is inserted into the cavity 120. As described above, this final portion of the air path can be provided, for example, by gaps (clear space) between protrusions (not shown) that are part of the inner surface of the receiving cavity 120 and are used to provide clamp retention of article 190 in the cavity 120. At the surface of the distal end (bottom) of the receiving cavity 120, the air path is redirected in the proximal direction—as illustrated by the curved arrows 181 in Figure 1—such as to enter the substrate element 192 of the aerosol-generating article 190.From there, the air path further extends through the various elements 192, 193, 194 and 195 of article 190 where it finally exits system 1, as described above with respect to aerosol generating article 190. Consequently, when a user takes a puff, i.e., when negative pressure is applied to the filter element 195 of article 190 received in cavity 120, air is drawn into the receiving cavity 120 at the edge of the insertion opening 122 and QfrdAnn / zznz / E / YiAi further along the air path into the lower portion at the distal end of the receiving cavity 120. There, the airflow enters the aerosol-generating article 190 through the substrate element 192 and further passes through the support element 193, the aerosol cooling element 194, and the filter element 195 where it finally exits the article 190. Thus, when the induction heating device is switched on, the vaporized material from the aerosol-forming substrate is drawn into the airflow through the substrate element 192 and is subsequently cooled in its further direction through the support element 193, the aerosol cooling element 194, and the filter element 195 such as to form an aerosol. To allow proper redirection of airflow within the aerosol-generating article 190 into the lower portion of the receiving cavity 120, the aerosol-generating device 100 may comprise one or more end stops (not shown) that can be arranged in the distal end portion of the receiving cavity 130 such as to limit the insertion depth of article 190 into the cavity 120 and thereby prevent article 190 from abutting the distal surface 123 of the receiving cavity 120. As mentioned previously, detecting the appropriate puff is important to ensure precise control of the heating process. For this purpose, the aerosol generating device 100 according to the present embodiment comprises a puff detector consisting of a vibration sensor 170 for detecting the sound caused by the airflow through the air path 180, 181 of the device 100, which in turn indicates a user taking a puff. In the present embodiment, the vibration sensor 170 is a microphone, for example, a moving-coil microphone. As can be seen in Figure 1, the vibration sensor 170 is disposed outside the receiving cavity 120, fluidly separated from the air path 180, 181 passing through the device 100. Due to this separate arrangement, the vibration sensor 170 is not exposed to the conditions of the air path, such as temperature and humidity.In particular, the 170 vibration sensor is isolated from. QfrdAnn / zznz / E / YiAi suspended particles or droplets originating from aerosol formation are protected from deposition. In the present embodiment, the vibration sensor 170 is arranged in a compartment 125 in the distal portion 101, which also includes the power source 150 and the electrical circuit 151, including the controller 152, as previously mentioned. The compartment 125 is fluidly separated from the receiving cavity 120 in the proximal portion 102 of the device 100. To enhance the sound effects indicative of airflow through the device 100 and used to identify a user's puff, the aerosol generating device 100 further comprises a sound-generating member 160. The sound-generating member 160 is arranged in fluid communication with the air path 180, 181 described above and is configured to generate sound caused by the airflow passing the sound-generating member 160 when a user takes a puff. In the present embodiment, the sound-generating member 160 comprises a sound-generating displacement structure configured to displace the airflow 181 at least partially when it passes the sound-generating displacement structure. Figure 2, Figure 3, and Figure 4 show details of the sound-generating displacement structure 161 implemented in the device according to Figure 1. In the present embodiment, the sound-generating displacement structure 161 comprises a one-dimensional array of ridges 162 arranged in a periodic pattern at the distal end of the receiving cavity 120 (Figure 2-4 not to scale). Slots 163 are formed between each of the two adjacent ridges 106. The cross-sectional shape of the ridges 162 is substantially triangular, such that each ridge 162 has a sharp edge on its upper surface. QfrdAnn / zznz / E / YiAi Therefore, when the airflow 182 passes the sound-generating displacement structure 161, the airflow 182 is partially displaced due to collisions with the crests 162 of the displacement structure 161, causing a portion of the airflow 180 to become turbulent, as shown in Figure 2. Because of this, some of the kinetic energy of the airflow, i.e., the dynamic pressure, is transformed into static pressure, resulting in a plurality of alternating high- and low-pressure regions 185, 186, as shown in Figure 3. The alternating pattern of adiabatic compressions and decompressions in the airflow 180 gives rise to an acoustic wave, i.e., sound, which propagates through the device 100. From the sound-generating displacement member 161, the acoustic wave propagates—among other things—through the wall member 111 that fluidly separates the receiving cavity. 120 of compartment 125.The acoustic wave propagates further through the air within compartment 125 until it reaches the vibration sensor 170. There, the acoustic wave (sound) is detected, indicating the presence of airflow through device 100, which, in turn, indicates that the user is taking a breath. As such, the sound-generating displacement structure 161 is part of a wall member, namely wall member 111, which defines at least a portion of the air path through device 100. In addition to the vibration sensor 170, the puff detector further comprises an electrical circuit that is operatively coupled to the vibration sensor 170 and configured to convert the output signal from the vibration center 170 into a signal indicating the presence of airflow in the receiving cavity 120. The electrical circuit may further comprise one or more electronic filters for filtering the output signal from the vibration sensor. Advantageously, the filtering can reduce various types of noise, particularly parasitic noise detected by the vibration sensor 170. The electrical circuit of the puff detector may be an integral part of the electrical circuit 151 that includes the controller 152.Based on the signal indicating the presence of airflow through device 100, the controller 152 can adjust the heating process control to maintain the heating temperature of the substrate 191 in item 190 at a certain level when a user takes a puff. QfrdAnn / zznz / E / YiAi The length 164 of the periodic pattern of the sound-generating displacement structure 161, as shown in Figure 4, is chosen to generate a sound in a specific frequency range depending on the airflow velocity 182. For example, if the airflow velocity 182 in the sound-generating displacement structure 161 is approximately 10 meters per second, and the displacement structure 161 comprises ridges 162 that appear every 0.25 millimeters, the sound has a frequency of approximately 40 kilohertz (kHz). This frequency is outside the range audible to humans and also outside the range audible to many animals, particularly pets such as dogs or cats. Figure 5 shows a second embodiment of the aerosol-generating device 100 according to the present invention. In this embodiment, the vibration sensor 270 is coupled to the wall member 211 that fluidly separates the receiving cavity 220 from the compartment 225. That is, the vibration sensor 270 is disposed on one side of a wall member 211 opposite a side of that wall member 211 that defines at least a portion of the air path through the device 200 and that also forms or at least supports the sound-generating displacement structure 261. Consequently, the vibration sensor 270 is closer to, and in particular directly coupled to, the sound-generating displacement structure 261, i.e., to the sound source. Advantageously, this configuration improves the detectability of the sound propagating through the device 100.Apart from that, the conformity modality shown in Figure 5 is identical to the first modality shown in Figure 1-3. Accordingly, identical or similar characteristics are indicated by the same reference numbers, but increased by 100. For the purposes of this description and the accompanying claims, unless otherwise stated, all numbers expressing quantities, percentages, etc., shall be understood as modified in all cases by the term approximately. Furthermore, QfrdAnn / zznz / E / YiAi All intervals include the maximum and minimum points described and include any intermediate intervals therein, which may or may not be specifically listed in this description. In this context, therefore, a number A is understood as A ± 5% of A.

Claims

1. The electrically operated aerosol generating device for generating an aerosol, the device comprising: - a receiving cavity for detachably receiving an aerosol-forming substrate or at least a portion of an aerosol-generating article comprising an aerosol-forming substrate; - an air path extending through the device and configured to support an airflow in the device; - a sound-generating member disposed in fluid communication with the air path and configured to generate sound caused by an airflow passing the sound-generating member during use of the device when a user takes a puff, wherein the sound-generating member is located in a distal end portion of the receiving cavity;and - a puff detector comprising a vibration sensor, wherein the vibration sensor is fluidly separated from the air path and configured to detect sound propagating from the sound-generating member to the vibration sensor.; 2. The aerosol generating device according to claim 1, wherein the sound generating member comprises a sound generating displacement structure for at least partially displacing the airflow when passing the sound generating displacement structure.

3. The aerosol generating device according to claim 2, wherein the sound-generating displacement structure comprises at least one of: one or more grooves or one or more ridges, one or more dimples, or one or more protrusions.

4. The aerosol generating device according to claim 3, wherein a longitudinal extension of one or more grooves, or a longitudinal extension of one or more ridges, or a longitudinal extension of one or more grooves and a longitudinal extension of one or more ridges is perpendicular to a direction of airflow passing the sound generating member during use of the device.

5. The aerosol generating device according to any one of claims 3 to 4, wherein the one or more grooves, or the one or more ridges, or the one or more grooves and the one or more ridges comprise one of: a triangular shape, a sinusoidal shape, or a rectangular shape.

6. The aerosol generating device according to any one of claims 3 to 5, wherein at least one of a ridge height or a groove depth varies, in particular increases along the sound-generating displacement structure in a direction of airflow passing the sound-generating member during use of the device.

7. The aerosol generating device according to any one of claims 2 to 6, wherein the sound-generating displacement structure is part of a wall member that defines at least a portion of the air path through the device.

8. The aerosol generating device according to any one of claims 2 to 7, wherein the sound-generating displacement structure comprises a periodic pattern.

9. The aerosol generating device according to claim 8, wherein the periodic pattern has a period length in the range of 0.1 millimeters to 2 millimeters, particularly between 0.2 millimeters and 1 millimeter, preferably between 0.25 millimeters and 0.5 millimeters.

10. The aerosol generating device according to any one of the preceding claims, wherein the sound generating member comprises at least one airflow-driven vibrating element configured to periodically interrupt an airflow passing through the vibrating element.

11. The aerosol generating device according to claim 10, wherein the at least one vibrating element comprises a sheet or a lamella or a pair of sheets or a pair of lamellae.

12. The aerosol generating device according to any one of the preceding claims, wherein the air path and the sound generating member are configured so that the sound generated during use of the device is in a frequency range above 15 kilo-Hertz, preferably above 20 kilo-Hertz, more preferably above 40 kilo-Hertz.

13. The aerosol generating device according to any one of the preceding claims, wherein the vibration sensor comprises a microphone, an accelerometer, an extensometer, or a piezoelectric transducer or an acoustic magnetic transducer.

14. The aerosol generating device according to any one of the preceding claims, wherein the vibration sensor is disposed on one side of a wall member opposite one side of the wall member that defines at least a portion of the air path through the device.

15. The aerosol generating device according to any one of the preceding claims, wherein the sound generating member is located on a distal end surface of the receiving cavity.

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