Low-latency communication protocol for binaural applications
Hearing instruments, such as hearing aids, may improve a quality of presented audio through the use of a binaural application, such as beamforming. The binaural application may require communication between the hearing instruments so that audio from a left hearing instrument may be combined with audio from a right hearing instrument. The combining at a hearing instrument can require synchronizing audio sampled locally with sampled audio received from wireless communication. This synchronization may cause a noticeable delay of an output of the binaural application if the latency of the wireless communication is not low (e.g., a few samples of delay). Presented herein is a low-latency communication protocol that communicates packets on a sample-by-sample basis and that compensates for delays caused by overhead protocol data transmitted with the audio data.
1. A method for wireless communication between two devices, the method comprising:
designating a first device as a master and a second device as a slave, wherein the master and the slave communicate data over a frame by:
transmitting protocol packets from the master to the slave at regular intervals in a first half of the frame and from the slave to the master at regular intervals in a second half of the frame, each protocol packet adding a latency to the wireless communication;
during the regular intervals between the protocol packets, transmitting data packets between the master and the slave in an alternating fashion, the data packets having a number of bits smaller than a number of bits of the protocol packets so that the latency added by each protocol packet is compensated for by the data packets transmitted between the protocol packets.
2. The method for wireless communication between two devices according to claim 1 , wherein the two devices are a left hearing instrument and a right hearing instrument.
3. The method for wireless communication between two devices according to claim 1 , wherein:
each protocol packet includes protocol data, audio data, and parity data;
each data packet includes audio data and parity data; and
the latency added by each protocol packet corresponds to a time necessary to transmit the protocol data.
4. The method for wireless communication between two devices according to claim 3 , wherein:
the protocol data is preamble data, synchronization data, message data, or cyclic redundancy check (CRC) data; and
the audio data is a sample of an audio signal.
5. The method for wireless communication between two devices according to claim 3 , wherein the protocol data is 16 bits.
6. The method for wireless communication between two devices according to claim 5 , wherein the latency is less than 200 microseconds.
7. The method for wireless communication between two devices according to claim 5 , wherein a number of data packets transmitted during the regular intervals between the protocol packets and a packet transmission rate of the data packets during the regular intervals between the protocol packets offset the latency added by each protocol packet.
8. The method for wireless communication between two devices according to claim 3 , wherein the audio data is encoded.
9. The method for wireless communication between two devices according to claim 1 , wherein the master and the slave communicate data using near field magnetic induction (NFMI).
10. The method for wireless communication between two devices according to claim 1 , wherein each protocol packet and each data packet includes one sample of audio so that each sample is transmitted individually on a sample-by-sample basis to reduce the latency in the wireless communication.
11. The method for wireless communication between two devices according to claim 1 , further comprising:
synchronizing the wireless communication between the master and the slave, wherein the synchronizing includes:
transmitting, at the master, protocol packets at regular intervals in a first half of a start-up frame; and
during the regular intervals between protocol packets transmitting data packets and repeating-pattern data packets in alternating fashion.
12. The method for wireless communication between two devices according to claim 11 , further comprising:
listening, at the master, for protocol packets from the slave at regular intervals in a second half of the start-up frame.