AUDIO PROCESSING IN A PORTABLE LISTENING DEVICE

• US 20110019838A1
• Filed: 01/20/2010
• Published: 01/27/2011
• Est. Priority Date: 01/23/2009
• Status: Active Grant

• Current Assignee: Oticon A/S (William Demant Fonden)
• Original Assignee: Oticon A/S (William Demant Fonden)
• Inventors: Skovby, Lars, Kaulberg, Thomas
• Granted Patent: US 8,929,566 B2
• Time in Patent Office: Days
• US Class Current: 381/98
• CPC Class Codes: G10L 2021/065 Aids for the handicapped in understanding
• CPC Class Codes: G10L 21/038 using band spreading techniques
• CPC Class Codes: H04R 1/10 Earpieces; Attachments therefor ; Earphones; Monophonic headphones H04R1/28 takes precedence; stereophonic headphones H04R5/033
• CPC Class Codes: H04R 2420/07 Applications of wireless loudspeakers or wireless microphones
• CPC Class Codes: H04R 2460/03 Aspects of the reduction of energy consumption in hearing devices
• CPC Class Codes: H04R 25/43 Electronic input selection or mixing based on input signal analysis, e.g. mixing or selection between microphone and telecoil or between microphones with different directivity characteristics H04R25/407 takes precedence
• CPC Class Codes: H04R 25/505 using digital signal processing
• CPC Class Codes: H04R 25/554 using a wireless connection, e.g. between microphone and amplifier or using Tcoils
• CPC Class Codes: H04R 5/033 Headphones for stereophonic communication details thereof, e.g. relating to batteries, cables or control elements H04R1/10
• CPC Class Codes: H04R 5/04 Circuit arrangements, e.g. for selective connection of amplifier inputs/outputs to loudspeakers, for loudspeaker detection, or for adaptation of settings to personal preferences or hearing impairments combinations of amplifiers H03F3/68; stereophonic systems H04S

Abstract

The invention relates to a method of processing an audio signal in a portable listening device, the audio signal comprising a low frequency part having an LF-bandwidth Δf_LF and a high-frequency part having a HF-bandwidth Δf_HF. The invention further relates to a listening device and to a listening system. The object of the present invention is to improve performance or save power in a portable listening device. The problem is solved in that the method comprises a) providing an audio input signal consisting of said low frequency part having an LF-bandwidth Δf_LF; b) performing at least one signal processing step on the low frequency part of the audio signal; and c) performing a bandwidth extension process on said low frequency part of the audio signal to generate said high-frequency part of the audio signal, thereby generating or regenerating said audio output signal with a full bandwidth Δf_full comprising said LF-bandwidth Δf_LF and said HF-bandwidth Δf_HF. An advantage of this is that power consumption is reduced. The invention may e.g. be used for portable communication device, mobile telephones or listening devices, such as a hearing aids, ear protection devices, headsets, head phones, etc.

Claims

1. A method of processing an audio signal in a portable listening device, the audio signal comprising a low frequency part having an LF-bandwidth Δ

f_LF and a high-frequency part having a HF-bandwidth Δ

f_HF, the method comprising a) providing an audio input signal consisting of said low frequency part having an LF-bandwidth Δ

f_LF;

b) performing at least one signal processing step on the low frequency part of the audio signal; and

c) performing a bandwidth extension process on said low frequency part of the audio signal to generate said high-frequency part of the audio signal, thereby generating or regenerating an audio output signal with a full bandwidth Δ

f_full comprising said LF-bandwidth Δ

f_LF and said HF-bandwidth Δ

f_HF.

2. A method according to claim 1 wherein the high-frequency part of the signal is generated by spectral band replication.

3. A method according to claim 1 wherein the LF-bandwidth and the HF-bandwidth together constitute the full bandwidth.

4. A method according to claim 1 wherein the at least one signal processing step comprises one or more, such as a majority or all of the following signal processing steps (a) introducing frequency dependent gain, (b) compression, (c) noise reduction, (d) feedback suppression, or (e) extraction of directionality information.

5. A method according to claim 1 wherein the low frequency part of the audio signal or a part thereof is picked up by a microphone of the portable listening device and possibly filtered by a low pass filter and/or digitized with an appropriate sample frequency.

6. A method according to claim 1 wherein the low frequency part of the audio signal or a part thereof is received by the portable listening device from another device.

7. A method according to claim 6 wherein the low frequency part of the audio signal or a part thereof is received by the portable listening device via a wireless interface.

8. A method according to claim 1 wherein the full bandwidth audio signal is fed to an output transducer, e.g. a receiver, for presentation to a wearer of the listening device.

9. A method according to claim 1 wherein the listening device is a hearing aid.

14. A portable listening device according to claim 10 adapted to provide a full bandwidth output signal according to the method of claim 1.

10. A portable listening device, comprising a signal processor adapted for processing a low frequency bandwidth input audio signal and providing a processed low bandwidth signal and a bandwidth extension unit adapted to provide a full bandwidth output signal based on the processed low bandwidth signal.

11. A portable listening device according to claim 10 further comprising a microphone for converting an input sound to an electric input signal and a low pass filter and/or an A/D-converter for converting the electric input signal to a digital input signal for generating the low frequency bandwidth input audio signal or a part thereof from the electric input signal.

12. A portable listening device according to claim 10 further comprising an output transducer, e.g. a receiver, for presenting the full bandwidth output signal to a wearer of the listening device.

13. A portable listening device according to claim 10 comprising a wireless interface adapted to receive said low frequency bandwidth input audio signal or a part thereof from another device via a wireless link.

15. A portable listening device according to claim 10 comprising an analyzing unit for determining a type of input signal and for providing a control signal indicative of said type, and wherein the bandwidth extension unit comprises several different schemes for providing bandwidth extension depending on said control signal.

16. A portable listening device according to claim 13, further comprising:

a microphone for converting an input sound to an electric input signal and a low pass filter and/or an A/D-converter for converting the electric input signal to a digital input signal for generating the low frequency bandwidth input audio signal or a part thereof from the electric input signal; and

a selector or mixing unit receiving inputs from the microphone and the wireless interface, the selector or mixing unit being adapted for providing as an output one of the inputs or a weighted mixture of the inputs.

22. A listening system according to claim 17 wherein said first portable listening device comprises a portable listening device according to claim 10.

17. A listening system comprising first and second devices, the first device being a portable listening device adapted for presenting an electrical output audio signal to a wearer of the first listening device, the electrical output audio signal having a full bandwidth Δ

f_full comprising a low frequency part and a high frequency part, wherein the second device comprises a wireless transmitter for wirelessly transmitting the low frequency signal and the first device comprises a) a wireless receiver for receiving said low frequency signal and b) a bandwidth extension unit for constructing or re-generating a high-frequency part of the electrical output audio signal, the high-frequency part having a HF-bandwidth Δ

f_HF, and for forming the electrical output audio signal having a full bandwidth Δ

f_full based on or comprising said low frequency signal having an LF-bandwidth Δ

f_LF and said high frequency signal having a HF-bandwidth Δ

f_HF.

18. A listening system according to claim 17 wherein the first device comprises a signal processor adapted for processing the low frequency input signal and providing a processed low frequency output signal to the bandwidth extension unit.

19. A listening system according to claim 17 wherein the second device comprises an input transducer for converting an input sound to an electric input signal and a frequency limiting unit, e.g. a low pass filter and/or an A/D conversion unit, for generating said low frequency part of a signal having an LF-bandwidth Δ

f_LF for being wirelessly transmitted to the first device.

20. A listening system according to claim 17 wherein the second device comprises an electric interface for receiving a signal comprising an audio signal and providing an electric input signal, and a frequency limiting unit, e.g. a low pass filter and/or an A/D conversion unit, for generating said low frequency part of a signal having an LF-bandwidth Δ

f_LF for being wirelessly transmitted to the first device from said electric input signal.

21. A listening system according to claim 17 wherein said wireless transmitter and receiver are adapted to provide an inductive coupling between the first and second device on which said transmission of said low frequency signal can be based, when said first and second devices are located in an operational distance from each other.