SADI 2007 - StoryTelling - Week38 Reproducing Sound 2

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Idea

Learn about the use of sound in different expressive ways. The goal of the day will be to create a prototype telling a story out of small space. Movements and sounds can be combined in the creation of contemporary music boxes.

Sound can be modified in frequency and volume. We use PWM to produce sound directly from microprocessors. More modern devices offer the possibility of reproducing sound files using external storage devices.

Agenda for the day

Today's topic

We are in the exploration of the use of sound. There are different devices that can be used in the creation of interactive objects producing sound. We will study the tools needed for sound reproduction, ways for integrating sound in the prototypes and reproduction of MP3 quality sound from external devices.

On the interaction side of the work, we will learn the magic behind touch sensors and will learn how to create simple interactive touch surfaces.

 Examples to come 

Digital Sound & Tools

Digital sound has different connotations for the users and for the technologists. There are tools to generate sound in real time, to record sound, to reproduce sound, to stream sound life on the internet, etc.

Here we will analyze the use of a couple of basic tools for recording/reproducing and synthesis of sound. There is a strong community of producers of semi-professional tools that will enhance the work made for many projects. We are going to focus in the use of two different tools:

• Audiacity: download the right version for your operating system from here, and don't forget the Lame encoder that will allow you to store your files as MP3
• Puredata: download the software from this site

Sound Surgery

Experiment creating the soundtrack of (a)Life products, express how a digital object sounds. You can choose to express the values of the product, the sequence of use, summarize the user experience, or just make a radio ad for it. Choose your product carefully and get it a beautiful soundtrack.

The experiment threw the following results, you may hear some interferences between melodies, we had no sound studio to record these hits.

Code example touch sensors

The brand QPROX manufactures different types of sensor that go from single touch to full keyboards. It is possible to hide the technology behind any type of non-conductive materials like wood, plastics, cardboard, or glass. Here we will use a QT118 single touch sensor as the activator

 int inputPin = 13;
int ledPin = 8;
int val;

void setup(){
  Serial.begin(9600);
  pinMode(inputPin, INPUT);
  pinMode(ledPin, OUTPUT);
}

void loop(){
  val = digitalRead(inputPin);
  if(val == HIGH){
    digitalWrite(ledPin, HIGH);
  }else{
    digitalWrite(ledPin, LOW);
  }
}

Code example for a melody player

It is possible to make very simple melody players with fairly good sound quality directly from a microprocessor. In this example we are going to build up our own small amplifier and attack it with the sound coming out from a digital pin in the Arduino board.

This example is making use of the following techniques:

• Serial library: Serial.available(), Serial.read()
• analog output: fading control through PWM
• Software commands: analogWrite(pin, value), delayMicroseconds(time)
• Components: sound speaker
• Sound production: period = 1/frequency, generating tones
• examples: Play Melody, Keyboard Serial

Code example to play from MP3 players

There exist a whole range of MP3 players that can be controlled from the serial port in a microcontroller. In this example we will use a new type of player that can play files stored in a USB-flash disk.

//MP3 control
int skipPin = 12;
int playPausePin = 13;
int val = 1;
int isPlaying = 0;
int isBeginning = 1;

void setup(){
  Serial.begin(9600);
  pinMode(skipPin, INPUT);
  pinMode(playPausePin, INPUT);
}


void loop(){
  val = digitalRead(playPausePin);
  if(val == LOW){
    if(isBeginning == 1){
      Serial.print("V3A"); //play all files
      Serial.print(13,BYTE);
      isPlaying = 1;
      isBeginning = 0;
      delay(500);
    }else{
      if(isPlaying == 1){
        Serial.print("E"); //pause
        isPlaying = 0;
        delay(500);
      }else{
        Serial.print(13,BYTE);  //resume
        isPlaying = 1;
        delay(500);    
      }
    }
  }

  val = digitalRead(skipPin);
  if(val == LOW){
    if(isPlaying == 1){
      Serial.print("VSF"); //Skip forward one track
      Serial.print(13,BYTE);
      isPlaying = 1;
      delay(500);
    }
  }
}