Automatic sound pass-through method and system for earphones
Earphone systems and methods for automatically directing ambient sound to an earphone device are provided. An ambient microphone signal from an ambient microphone proximate a sound isolating earphone or headset device is directed to a receiver within an earphone device according to mixing circuitry. The mixing circuitry is controlled by voice activity of the earphone device wearer. This enables hands-free operation of an earphone system to allow the earphone device wearer to maintain situation awareness with the surrounding environment. During detected voice activity, incoming audio content is attenuated while ambient sound is increased and provided to the earphone device. User voice activity is detected by analysis of at least one of an ear canal microphone signal or an ambient sound microphone signal.
1. A method for passing ambient sound to an earphone device configured to be inserted in an ear canal of a user, the method comprising the steps of:
capturing the ambient sound from an ambient sound microphone (ASM) proximate to the earphone device to form an ASM signal;
receiving an audio content (AC) signal from a remote device;
detecting voice activity of the user of the earphone device;
mixing the ASM signal and the AC signal to form a mixed signal, such that, in the mixed signal, an ASM gain of the ASM signal is increased and an AC gain of the AC signal is decreased when the voice activity is detected;
detecting a cessation of the voice activity;
delaying modification of the ASM gain and the AC gain for a predetermined time period responsive to the detected cessation of the voice activity; and
directing the mixed signal to an ear canal receiver (ECR) of the earphone device.
2. The method according to claim 1 , wherein the mixing of the ASM signal and the AC signal includes decreasing the ASM gain of the ASM signal and increasing the AC gain of the AC signal when the voice activity is not detected.
3. The method according to claim 1 , wherein the AC gain and the ASM gain are selected according to whether the voice activity is detected.
4. The method according to claim 3 , wherein the mixing of the ASM signal and the AC signal includes:
applying the ASM gain to the ASM signal to generate a modified ASM signal;
applying the AC gain to the AC signal to generate a modified AC signal; and
mixing the modified ASM signal and the modified AC signal to form the mixed signal.
5. The method according to claim 1 , wherein each of the AC gain and the ASM gain is greater than zero and less than or equal to unity gain.
6. The method according to claim 1 , wherein the AC signal is received from the remote device via a wired connection or a wireless connection.
7. A method for passing ambient sound to an earphone device configured to be inserted in an ear canal of a user, the method comprising the steps of:
capturing the ambient sound from an ambient sound microphone (ASM) proximate to the earphone device to form as ASM signal;
receiving an audio content (AC) signal from a remote device;
detecting voice activity of the user of the earphone device, wherein the detecting of the voice activity includes:
determining a time-smoothed level of a microphone signal to form a microphone level;
comparing the microphone level with a predetermined microphone level threshold; and
detecting the voice activity when the microphone level is greater than the microphone level threshold; and
mixing the ASM signal and the AC signal to form a mixed signal, such that, in the mixed signal, an ASM gain of the ASM signal is increased and an AC gain of the AC signal is decreased when the voice activity is detected.
8. The method according to claim 7 , wherein the detecting of the voice activity includes detecting the voice activity from the microphone signal, the microphone signal including at least one of the ASM signal or an ear canal microphone (ECM) signal captured within the ear canal from an ECM of the earphone device.
9. The method according to claim 8 , the method including filtering at least one of the microphone signal or the AC signal by a predetermined filtering characteristic.
10. The method according to claim 7 , wherein the detecting of the voice activity includes:
determining a time-smoothed level of the AC signal to form an AC level;
comparing the AC level with an AC level threshold; and
detecting the voice activity when the microphone level is greater than the microphone level threshold and the AC level is less than the AC threshold.
11. The method according to claim 10 , wherein the AC threshold value is modified by a predetermined AC gain coefficient value.
12. The method according to claim 8 , wherein the detecting of the voice activity includes:
adaptively filtering the AC signal to form a filtered AC signal;
determining a difference between the microphone signal and the filtered AC signal to form an error signal;
determining a time-smoothed level of the error signal to form an error level;
comparing the error level with an error threshold; and
detecting the voice activity when the error level is greater than the error level threshold.
13. An earphone system comprising:
at least one earphone device including:
a sealing section configured to conform to an ear canal of a user of the earphone device;
an ear canal receiver (ECR);
an ambient sound microphone (ASM) for capturing ambient sound proximate to the earphone device and to form an ASM signal;
a signal processing system configured to:
receive an audio content (AC) signal from a remote device,
detect voice activity of the user of the earphone device,
mix the ASM signal and the AC signal to form a mixed signal, such that, in the mixed signal, an ASM gain of the ASM signal is increased and an AC gain of the AC signal is decreased when the voice activity is detected, and
direct the mixed signal to the ECR; and
a voice activity detector (VAD) timer system configured to:
detect a cessation of the voice activity, and
delay modification of the ASM gain and the AC gain for a predetermined time period responsive to the detected cessation of the voice activity.
14. The earphone system according to claim 13 , wherein the at least one earphone device includes at least two earphone devices.
15. The earphone system according to claim 13 , wherein the remote device includes at least one of a mobile phone, a radio device, a computing device, a portable media player, an earphone device of a different user or a further earphone device of the user.
16. The earphone system according to claim 13 , further comprising a communication system configured to receive the AC signal from the remote device via a wired or wireless connection.
17. The earphone system according to claim 13 , wherein the signal processing system is further configured to decrease the ASM gain of the ASM signal and increase the AC gain of the AC signal prior to mixing the ASM signal and the ASM signal when the voice activity is not detected.
18. The earphone system according to claim 13 , further comprising:
a voice activity detector (VAD) system configured to detect the voice activity from a microphone signal, the microphone signal including at least one of the ASM signal or an ear canal microphone (ECM) signal captured within the ear canal from an ECM of the earphone device.
19. The earphone system according to claim 18 , wherein the VAD system is configured to:
determine a time-smoothed level of the AC signal to form an AC level,
compare the AC level with an AC level threshold, and
detect the voice activity when the microphone level is greater than the microphone level threshold and the AC level is less than the AC threshold.
20. The earphone system according to claim 19 , wherein the VAD system is configured to:
determine a time-smoothed level of the AC signal to form an AC level,
compare the AC level with an AC level threshold, and
detect the voice activity when the microphone level is greater than the microphone level threshold and the AC level is less than the AC threshold.
21. The earphone system according to claim 18 , wherein the VAD system is configured to:
adaptively filter the AC signal to form a filtered AC signal,
determine a difference between the microphone signal and the filtered AC signal to form an error signal,
determine a time-smoothed level of the error signal to form an error level,
compare the error level with an error threshold, and
detect the voice activity when the error level is greater than the error level threshold.