GB2538165A

GB2538165A - Audio communication apparatus

Info

Publication number: GB2538165A
Application number: GB1606340.6A
Authority: GB
Inventors: Donaldson Mark; Darlington Paul
Original assignee: Soundchip SA
Current assignee: Soundchip SA
Priority date: 2015-04-13
Filing date: 2016-04-13
Publication date: 2016-11-09
Also published as: GB201506206D0

Abstract

A communication apparatus that includes a voice collection microphone and at least one speaker configured to reproduce sound at an ear of the user; and an audio processor connected to the apparatus to receive signals from the microphone and deliver signals to the speaker, in which the audio processor causes a sidetone signal to be delivered to the speaker for reproduction thereby in combination with an audio signal received from a remote source; wherein the audio processor is operative to determine the loudness of a voice of a user of the apparatus from the signal collected by the microphone and to alter a characteristic of the sidetone signal based on that determination. The characteristic altered by the signal processor may include causing a relatively fast growth in sidetone volume when the determined loudness is excessive according to predetermined criteria. By adapting the sidetone signal based upon determined loundness, it is possible to influence the users speech and discourage the user from speaking excessively loudly. A passenger on an in-flight entertainment and communication (IFEC) system may be provided with a headset which encourages the passenger to speak softly during a telephone conversation so as not to disturb others nearby.

Description

Audio Communication Apparatus This invention relates to audio communication apparatus. It has particular, but not exclusive, application to audio communication apparatus that is suitable for use in voice telephony in an environment of variable ambient noise such as the cabin of an aircraft Recent advances in in-flight entertainment and communications (IFEC) technology allow the use of audio headsets by aircraft passengers, which not only provide audio programming but also enable voice telephony. However, some airlines are reluctant to offer in-flight voice telephony for fear that passengers, speaking loudly, will disrupt the ambience of the cabin environment. The loudness of a passenger's voice when engaged on a telephone call principally depends on how well they can hear themselves, which is a function of the level of ambient cabin noise, the degree of noise isolation offered by the headset being worn and the intelligibility of the received audio signal.

An aim of this invention is to provide an audio headset that encourages a passenger to speak softly during a telephone conversation so as not to disturb other passengers nearby.

Telephony headsets and handsets typically provide what is commonly referred to as "sidetone". Provision of sidetone in a telephony device involves feeding part of the measured passenger's voice signal back into the audio signal reproduced by the headset, so that a user of the device can hear their own speaking voice. Conventionally, sidetone is typically configured, in terms of level and spectral capture, such that it: (a) feeds back speech rather than ambient noise; and (b) reproduces this at a level, which is comfortable and typical of ordinary conversation.

Sidetone, in its most conventional form, does not address, nor assist in reducing, the loudness of the speaker voice as heard by others nearby. However, the present inventors have realised that control of sidetone has the potential to achieve a reduction in or limitation of such perceived loudness. The invention relies upon adjusting the level and spectral content of the sidetone signal so as to make listening to one's own voice less and less comfortable and one's speaking loudness increases beyond predefined criteria.

From a first aspect, this invention provides communication apparatus that includes a voice collection microphone and at least one speaker configured to reproduce sound at an ear of a user; and an audio processor connected to the apparatus to receive signals from the microphone and deliver signals to the speaker, in which the audio processor causes a sidetone signal to be delivered to the speaker for reproduction thereby in combination with an audio signal received from a remote source; wherein the audio processor is operative to determine the loudness of a voice of a user of the apparatus from the signal collected by the microphone and to alter a characteristic of the sidetone signal based on that determination.

By adapting the sidetone signal based upon determined loudness, it is possible to influence the user's speech and discourage the user from speaking excessively loudly.

The apparatus may be constituted by one or other of a headset and a handset The audio processor may execute a dynamic sidetone adjustment process which analyses the determined loudness and calculates how the sidetone should be altered such that when reproduced by the speaker encourages the user to speak at a (e.g. reduced) level of loudness that meets one or more criteria. The criteria may include instantaneous speech-to-noise ratio.

The signal processing means may be operative to execute the alteration in either the time or frequency domain.

The characteristic altered by the signal processing means may include causing a relatively fast growth in sidetone volume when the determined loudness is excessive according to predetermined criteria. Alternatively or additionally, the characteristic altered by the signal processing means includes one or more of short-term gain changes, filtering and delay.

The audio processor may further include means operable (at least in a telephone mode) to combine sidetone with an audio signal to be delivered to the speaker.

In use, the audio signal most typically includes a voice signal from the second party on a voice telephone call.

The apparatus can typically be operable in a telephone mode to receive voice audio from a near-end user and reproduce voice audio of a far-end user during the course of a telephone conversation.

Audio communication apparatus embodying the invention is typically suitable for use with an inflight entertainment and communications system (IFEC) installed on an aircraft From a second aspect, this invention provides an inflight entertainment and communications system (IFEC) installed on an aircraft that includes audio communication apparatus according to the last-preceding paragraph. Such an IFEC is typically capable of establishing a voice communication connection between a user of the audio communication apparatus and a second speaking party. The second speaking partymay be located on the aircraft or elsewhere.

From a third aspect, this invention provided a method of operating telephony apparatus, which apparatus that includes a voice collection microphone and at least one speaker configured to reproduce sound at an ear of a user, comprising receiving a signal from the microphone; analysing the received signal to determine the loudness of a speaker's voice, and adding a sidetone to a signal to be delivered to the speaker, in which a characteristic of the sidetone is determined by the determined loudness.

The loudness of a speaker's voice may be determined by measuring a speech to noise ratio.

In one embodiment the method comprises calculating how the sidetone should be altered such that when reproduced by the speaker encourages the user to speak at a (e.g. reduced) level of loudness that meets one or more criteria. The criteria may include instantaneous speech-to-noise ratio.

In such a method, the characteristic may include one or more of a short-term change in the gain of the sidetone, a change in the rate of gain of the sidetone, imposed changes in the frequency-domain relationship between the voice and the resulting sidetone and temporal shifts between the voice and the sidetone, including binaural delays.

An embodiment of the invention will now be described in detail, by way of example, and with reference to the accompanying drawings, in which: Figure 1 is a block diagram of an in-flight entertainment and communications (IFEC) system and a headset that embodies the invention; and Figure 2 is a block diagram that illustrates the operation of die system of Figure 1.

With reference to the drawings, an in-flight entertainment and communications (IFEC) system 10 is provided on board an aircraft Amongst other functions, the IFEC system 10 allows a user to make and receive voice telephone calls with others on board the aircraft or elsewhere. The operation of such a system is well understood by those in the technical field so will not be described further.

Each user of the IFEC system 10 is provided with a headset 12. The headset 12 includes two speakers 14 and at least one microphone for voice collection 16.

Each microphone can be dedicated exclusively for the purpose ofvoice collection, or, it may be shared to support the enablement of other audio functions when the headset is not configured for a telephone call. For instance, the voice collection microphone or microphones maybe used to enable the active noise cancellation of ambient sound where the headset comprises such technology whilst the headset is not being used for the purpose of telephony. Accordingly, so long as the voice collection microphones installed within the headset can be used to effectively capture voice when the user is speaking and the headset is configured to enable a telephone call, then they are deemed suitable for enabling the invention described herein.

Each speaker 14 is operable to receive an audio signal from the IFEC system and reproduce it as sound to be delivered to a respective one of a user's ears. The microphone(s) 16 is operable to receive sound of a user's speech and to deliver a corresponding audio signal to the IFEC system 10. A connection exists between the headset 12 and the IFEC system 10 to convey these audio signals and other signals as required.

During a voice telephone call, which may be initiated by a local "near-end" user making an outgoing call or by receipt of an incoming call from a remote "far-end" user, the headset 12 operates in a telephone mode in which the microphone 16 receives a user's speech and delivers a voice signal to the IFEC system 10 and the speakers receive a signal from the IFEC system 10 that contains the speech of a remote contact and reproduces this as audible sound. This operation is in full duplex.

The headset 12 additionally includes a sidetone module 30 that, in telephony mode, receives a signal from the microphone and delivers a signal to a mixer 32 where it is added to the voice signal that is delivered to the speakers 14.

In telephony mode, conventional noise-suppression algorithms, well known in the technical field, will depend upon the action of a near-end voice activity detector (VAD) 40 to control the user's sidetone signal. When VAD indicates near-end speech, the wearer hears his own voice: that is, a sidetone signal is provided. When VAD indicated far-end speech, the near-end user's own microphone and the ambient noise it detects are reduced in the sidetone signal presented to the near-end user.

When the VAD determines that the near-end user is speaking, her/his vocal level is tested against acceptable levels by comparison of short-term speech levels with long-term noise level measures to determine an instantaneous speech-to-noise ratio. Acceptability is judged as a function of instantaneous speech-to-noise ratio, as detected at the wearer's speech microphone.

The instantaneous speech-to-noise ratio during active telephony is used to derive a control parameter. The control parameter further adjusts the settings of an audio processor, that operates to derive the near-end user's sidetone signal from her/his own voice microphone 16. The control parameter is designed to have functional dependence upon speech-to-noise ratio such as to penalize loud speech, according to pre-determined characteristics.

The audio processor responds to the control parameter to change the sidetone signal in a manner which may include (but is not limited to) short-term gain changes (i.e. "volume" changes"), filtering (i.e. imposing changes in the frequency-domain relationship between the voice and the resulting sidetone) and delay (introducing temporal shifts between the voice and the sidetone, including binaural delays). This allows the audio processor to change the audio sidetone experienced by the user, without introducing perceptions of low audio quality.

The control parameter's dependence upon the speech-to-noise ratio and the audio processor may be designed so as to discourage loud speech (e.g. by providing an unnaturally fast growth of sidetone energy when the speech-to-noise level exceeds a certain threshold, as illustrated at 42 in Figure 2). This effect may be -by the means described above -introduced discretely and without prejudice to audio quality. This is illustrated in Figure 2.

The audio processor maybe implemented in analogue or digital domains, and comprise either fixed or programmable signal processing means and logic. Such may be physically embodied using conventional analogue electronics, analogue-gate-arrays, digital-signal-processors, or combinations thereof.