Method and device for spectral expansion for an audio signal
A method and device for automatically increasing the spectral bandwidth of an audio signal including generating a “mapping” (or “prediction”) matrix based on the analysis of a reference wideband signal and a reference narrowband signal, the mapping matrix being a transformation matrix to predict high frequency energy from a low frequency energy envelope, generating an energy envelope analysis of an input narrowband audio signal, generating a resynthesized noise signal by processing a random noise signal with the mapping matrix and the envelope analysis, high-pass filtering the resynthesized noise signal, and summing the high-pass filtered resynthesized noise signal with the original an input narrowband audio signal. Other embodiments are disclosed.
1. An earpiece, comprising:
a speaker;
an ear canal microphone;
an ambient sound microphone, wherein the ambient sound microphone is configured to measure sound further from the ear canal than the ear canal microphone when the earpiece is used;
a memory that stores instructions; and
a logic circuit that is configured to execute the instructions to perform operations, the operations comprising:
measuring sound received from the ear canal microphone or the ambient sound microphone or both;
detecting if a user is speaking by analyzing the measured sound;
extracting a narrowband input signal from the measured sound;
extracting a noise signal from the measured sound;
generating a mapping function comprising:
frequency transforming a high bandwidth reference signal into a set number (N) of frequency bands;
frequency transforming a low bandwidth reference signal into the set number (N) of frequency bands;
calculating the first set of N-envelopes of the frequency transformed high bandwidth reference signal in a dB/log domain;
calculating the second set of N-envelopes of the frequency transformed low bandwidth reference signal in the dB/log domain;
generating a mapping function by fitting a function to the first set of N-envelopes and the second set of N-envelopes;
generating a wideband output signal by applying the mapping function to the narrowband input signal; and
sending the wideband output signal to a remote device.
2. An earpiece according to claim 1 , wherein the mapping function takes the energy of frequency components between 3.5 kHz and 4 kHz and extends the energy to frequency components from 4 kHz to 8 kHz to generate the wideband output signal.
3. The earpiece according to claim 2 , further including the operations of:
analyzing the narrowband input to determine a voice command; and
initiating an action in response to the voice command.
4. An earpiece according to claim 3 , where the voice command is to create an audio content wish list.
5. An earpiece according to claim 3 , where the voice command is perform at least one of the following actions with respect to an audio content list stored in the memory, purchase a song in the audio content list, delete a song from the audio content list, skip to the next song in the audio content list, add a song to the audio content list, and delete the audio content list.
6. An earpiece according to claim 3 , where the voice command is to search the internet.
7. An earpiece according to claim 6 , where the internet search results are received via a text to speech analyzer resulting in an audio result and the user receives the audio result.
8. An earpiece according to claim 3 , where the voice command is to scan audio from the internet.
9. An earpiece according to claim 3 , where the voice command is to play audio from a radio station.
10. An earpiece according to claim 3 , where the voice command is to search for a particular stock value.
11. An earpiece according to claim 3 , where the voice command is to link to a user's investment account.
12. An earpiece according to claim 11 , where a second voice command is to search for a particular stock value.
13. An earpiece according to claim 12 , where a third voice command is to buy the particular stock.
14. An earpiece according to claim 12 , where a third voice command is to sell the particular stock.
15. The earpiece according to claim 3 including a second ambient sound microphone.
16. The earpiece according to claim 15 , further including a sealing section.
17. An earpiece according to claim 16 , further including the operations of: measuring the sound pressure level using the ear canal microphone.
18. An earpiece according to claim 17 , further including the operations of: calculating the sound pressure level dosage of a user using the measured sound pressure level.
19. An earpiece according to claim 3 , wherein the operation of detecting uses a portion of spectral components of the sound below 8 kHz.
20. An earpiece according to claim 19 , wherein the operation of detecting uses a portion of the spectral components of the sound below 4.5 kHz.
21. An earpiece according to claim 3 , further including:
a second ambient sound microphone.
22. An earpiece according to claim 1 , wherein the operation of generating a wideband output signal is performed by applying the mapping function to the narrowband input signal and the noise signal.