## Sound Analyser |

Electroacoustics / Acoustics |

A machine comprised of a filter system and a system for indicating the relative energy passed through each part of the filter. This measurement gives the distribution of energy of the applied signal as a function of frequency called the spectrum of the signal.

See: Sonography, Spectrograph. Compare: Fourier Analysis, Helmholtz Resonator, Level Recorder, Oscilloscope, Sound Level Meter.

There are many types of analysers. An *Octave Band Analyser* measures the intensity level for each of a set of
octave bands, centred on 31.5, 63, 125, 250, 500, 1000, 2000, 4000, 8000 and 16,000 Hz. A *Third-Octave Band
Analyser* divides the frequency spectrum into three bands per octave, the *Tenth-Octave Band Analyser* into
ten bands per octave.

See Broad Band Noise, Infrasonic, Spectrum, White Noise for examples of third-octave analyses. See: Centre Frequency. Compare: Critical Band, Appendix E.

Other types of analysers include the *Wave Analyser,* which is a continuously
variable analyser over the entire audio range; the *Impact Noise Analyser* for analysing impact sounds such as hammers or punch presses; and the *Vibration Analyser,* for
analysing infrasonic vibration.

Centre Frequency (Hz) |
Effective Band (Hz) |

31.5 |
22.1 - 44.2 |

63 |
44.2 - 88.4 |

125 |
88.4 - 177 |

250 |
177 - 354 |

500 |
354 - 707 |

1,000 |
707 - 1,414 |

2,000 |
1,414 - 2,828 |

4,000 |
2,828 - 5,657 |

8,000 |
5,657 - 11,314 |

Centre Frequency |
Centre Frequency |
Centre Frequency |

(Hz) |
(Hz) |
(Hz) |

10 |
100 |
1,000 |

12.5 |
125 |
1,250 |

16 |
160 |
1,600 |

20 |
200 |
2,000 |

25 |
250 |
2,500 |

31.5 |
315 |
3,150 |

40 |
400 |
4,000 |

50 |
500 |
5,000 |

63 |
630 |
6,300 |

80 |
800 |
8,000 |