Proj-2012-2013-Audioprothèse DIY 2/SRS

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1. Introduction

1.1 Purpose of the requirements document

This Software Requirements Specification (SRS) identifies the requirements for the hearing aid. In case of a open source project, we must present the requirement to others potential contributors. This document is a guideline about the functionalities offered and the problems that the system solves.

1.2 Scope of the product

  • The product we are developing is a low cost hearing aid. The goal is create an aid for evreybody without cost contraint.
  • We haven't vainglory to do an heading aid as the industrial hearing aid.
  • This project is totaly open-sorce and everybody can contribute at this.

1.3 Definitions, acronyms and abbreviations

  • Processor: It's the computer's heart. It execute the instruction and process data
  • Microprocessor: It's a mini processor wich is in a single integrated circuit
  • DSP: Digital Signal Processor is a specialized and optimized microprocessor
  • Microcontroller: It's a small computer on a single integrated circuit containing a processor core, memory, and programmable input/output peripherals.
  • PCM: Pulse-Code Modulation is a method used to digitally represent sampled analog signals. A PCM stream is a digital representation of an analog signal, in which the magnitude of the analog signal is sampled regularly at uniform intervals, with each sample being quantized to the nearest value within a range of digital steps. (wikipedia)
  • PDM: Pulse-Density Modulation is an other method used to digitally represent sampled analog signals. In a PDM signal, specific amplitude values are not encoded into pulses of different size as they would be in PCM. Instead, it is the relative density of the pulses that corresponds to the analog signal's amplitude. (wikipedia)

1.4 References

1.5 Overview of the remainder of the document

The rest of the SRS examines the specifications of the project in details.

2. General description

2.1 Product perspective

2.2 Product functions

  • amplifying sound
  • changing frequencies

2.3 User characteristics

  • Each user have different hearing problem and our device should adapt at the partucular user's problem.
  • The device should be configurable in order to fulfill the user needs without modifying any line of code.

2.4 General constraints

  • The langage using by the stm32f4 (c/c++) card which is low level.
  • The sound should be processed in real time

2.5 Assumptions and dependencies

  • The card doesn't work without computer, it hasn't battery
  • We do the assumption that the user know her hearin problem

3.Specific requirements, covering functional, non-functional and interface requirements

  • Document external interfaces,
  • Describe system functionality and performance
  • Specify logical database requirements,
  • Design constraints,
  • Emergent system properties and quality characteristics.

Requirement X.Y.Z (in Structured Natural Language)

Function: Help people with hearing problem at better listen to external sounds.

Description: The products consists of a program on a stm32F4 card.

Inputs: The alone input of our products is the external sound. It provided by the card's microphone.

Source: The differents demonstration created by STMicroelctronics

Outputs: The sound audible for the user it's return by the jack plug of the card and an earphone.

Destination: Everybody with simple hearing problems.


  • Save external sound by microphone
  • Treat the sound in numerics to respond at the user problem
  • Return the sound after treatment by earphone

Non functional requirements: none


  • Have a computer
  • Install the tools to developping on the stm32f4 card as show here
  • Know your hearing problem to choose the good correction

Post-condition: none


  • The earphone can disturb some people
  • A correction doesn't made to measure

4. Product evolution

5. Appendices

5.1 Specification

  • The global project's page can be found.
  • Three RICM4 groups are working on this project. Here are their wiki page:

5.2 Sources

5.3 Licensing Requirements

This project don't require a licence. It's an open project.