Method for synchronizing the reproduction of a digital signal sent by a transmitter to a plurality of mobile audio terminals

• US 9,860,654 B2
• Filed: 04/25/2016
• Issued: 01/02/2018
• Est. Priority Date: 04/24/2015
• Status: Active Grant

• Current Assignee: Sivantos Pte. Ltd. (WS Audiology A/S)
• Original Assignee: Sivantos Pte. Ltd. (WS Audiology A/S)
• Inventors: Zhang, Jie, Lampe, Mattias
• Primary Examiner(s): Le, Huyen D
• Application Number:
  US15/137,392
• Publication Number:
  US 20160316302A1
• Time in Patent Office: 617 Days
• Field of Search: 381 231, 381312, 381314, 381315, 381320, 381321, 381323, 375354, 375355, 370352
• CPC Class Codes: G06F 5/12 Means for monitoring the fill level; Means for resolving contention, i.e. conflicts between simultaneous enqueue and dequeue operations
• CPC Class Codes: H04J 3/0632 Synchronisation of packets and cells, e.g. transmission of voice via a packet network, circuit emulation service [CES] queuing arrangements in packet switching elements H04L49/90; synchronising systems for the synchronous transmission of a pulse code modulated video signal with one or more other pulse code modulated signals H04N7/56
• CPC Class Codes: H04L 25/0262 Arrangements for detecting the data rate of an incoming signal
• CPC Class Codes: H04L 7/0029 interpolation of received data signal
• CPC Class Codes: H04R 2225/43 Signal processing in hearing aids to enhance the speech intelligibility
• CPC Class Codes: H04R 2225/55 Communication between hearing aids and external devices via a network for data exchange
• CPC Class Codes: H04R 2420/07 Applications of wireless loudspeakers or wireless microphones
• CPC Class Codes: H04R 25/505 using digital signal processing
• CPC Class Codes: H04R 25/55 using an external connection, either wireless or wired
• CPC Class Codes: H04R 25/552 Binaural
• CPC Class Codes: H04R 25/554 using a wireless connection, e.g. between microphone and amplifier or using Tcoils
• CPC Class Codes: H04R 25/558 Remote control, e.g. of amplification, frequency
• CPC Class Codes: H04R 27/00 Public address systems circuits for preventing acoustic reaction H04R3/02; circuits for distributing signals to loudspeakers H04R3/12; monitoring or testing arrangements for public address systems H04R29/007; amplifiers H03F
• CPC Class Codes: H04W 28/0278 using buffer status reports dynamic wireless traffic scheduling definition H04W72/12

Abstract

A method for synchronizing the reproduction of a digital signal sent by a transmitter to a plurality of mobile audio terminals. The transmitter sends the digital signal as a multiplicity of data packets at a data rate that is constant as an average over time. A signal receiver of each mobile audio terminal receives at least a subset of the multiplicity of data packets and generates a time reference signal. A FIFO signal with information on an occupancy level of a FIFO memory of the mobile audio terminal at specific time points is generated, an instantaneous reproduction speed is set on the basis of the time reference signal and the FIFO signal, the audio reproduction unit reproduces at the instantaneous reproduction speed samples corresponding to the digital signal. The occupancy level of the FIFO memory is thereby kept constant as an average over time.

Claims

1. A method for synchronizing a reproduction of a digital signal sent from a transmitter to a plurality of mobile audio terminals, wherein each of the mobile audio terminals has a signal receiver, a First-In-First-Out memory connected to the signal receiver and an audio reproduction unit connected to the FIFO memory, the method comprising:

sending the digital signal from the transmitter as a multiplicity of data packets at a data rate that is constant as an average over time;

each mobile audio terminal in each case;

receiving with the signal receiver at least a subset of the multiplicity of data packets;

generating with the signal receiver a time reference signal from the received data packets;

generating from the FIFO memory a FIFO signal containing information on an occupancy level of the First-In-First-Out memory at specific time points;

setting an instantaneous reproduction speed on a basis of the time reference signal and the FIFO signal;

reproducing with the audio reproduction unit at the instantaneous reproduction speed samples corresponding to the digital signal; and

thereby keeping constant the occupancy level of the FIFO memory as an average over time.

4. The method according to claim 1, which comprises for each mobile audio terminal, determining the occupancy level of the FIFO memory at least approximately at each of the time points defined on the basis of the time reference signal, and generating the FIFO signal therefrom.

5. The method according to claim 4, which comprises, for each mobile audio terminal:

defining an upper limit and a lower limit for the occupancy level of the FIFO memory;

when the occupancy level exceeds the upper limit, increasing the instantaneous reproduction speed for a period defined on a basis of the time reference signal; and

when the occupancy level drops below the lower limit, decreasing the instantaneous reproduction speed for a period defined on the basis of the time reference signal.

6. The method according to claim 1, which comprises, for each mobile audio terminal:

defining an upper limit and a lower limit for the occupancy level of the FIFO memory;

when the occupancy level exceeds the upper limit, generating an overrun signal;

when the occupancy level drops below the lower limit, generating an underrun signal; and

generating the FIFO signal from the overrun signal and the underrun signal.

7. The method according to claim 6, which comprises, for each mobile audio terminal:

when the FIFO signal contains the overrun signal, increasing the instantaneous reproduction speed for a period defined on a basis of the time reference signal; and

when the FIFO signal contains the underrun signal, decreasing the instantaneous reproduction speed for a period defined on the basis of the time reference signal.

8. The method according to claim 1, which comprises, for each mobile audio terminal, setting the instantaneous reproduction speed according to the FIFO signal to a level defined on the basis of the time reference signal and/or the occupancy level of the FIFO memory.

2. The method according 1, which comprises:

combining with the transmitter respective groups of data packets into temporal frames;

wherein each frame has a time pattern containing a transmission time and a quiet time;

transmitting all the data packets in a frame during the transmission time; and

wherein the quiet time in each frame is longer than a time gap between any two data packets.

3. The method according to claim 2, which comprises generating with each signal receiver the time reference signal from a periodicity of the frames of data packets received by the signal receiver.

9. A hearing system, comprising:

a plurality of mobile audio terminals each containing a signal receiver, a First-In-First-Out memory and an audio reproduction unit; and

said mobile audio terminals being configured to implement a method for synchronizing a reproduction of a digital signal sent from a transmitter to the plurality of mobile audio terminals, the method including the following steps;

sending the digital signal from the transmitter as a multiplicity of data packets at a data rate that is constant as an average over time;

each mobile audio terminal in each case;

receiving with the signal receiver at least a subset of the multiplicity of data packets;

generating with the signal receiver a time reference signal from the received data packets;

generating from the FIFO memory a FIFO signal containing information on an occupancy level of the First-In-First-Out memory at specific time points;

setting an instantaneous reproduction speed on a basis of the time reference signal and the FIFO signal;

reproducing with the audio reproduction unit at the instantaneous reproduction speed samples corresponding to the digital signal; and

thereby keeping constant the occupancy level of the FIFO memory as an average over time.

10. The hearing system according to claim 9, comprising two hearing-aid devices forming a binaural hearing-aid apparatus.