Android audio applications

Signal generator 1.0.2

  • Outputs sine, pink noise, and white noise
  • Volume and frequency sliders
    • Controls are hard to grab at the edges
    • Volume control is independent from the phone’s volume control
    • Doesn’t go below 100 Hz
  • Sine waves are distorted and badly aliased at high frequencies.  THD+N measurements:
    • 100 Hz 0.149%
    • 1 kHz: 0.08%
    • 10 kHz: 7.1%
    • 20 kHz: 20.15%
    • Spectrum for 997 Hz:
    • signal generator 997 Hz
  • Although the control says “1.00 kHz” at startup, it’s actually playing 765 Hz.  Frequencies are correct after you start moving it around, though.
  • White noise level is higher than sine wave — sine wave never reaches the peak output of the phone, even at “0 dB”
  • There doesn’t seem to be any way to enter levels other than 0 dB manually, since it doesn’t let you type a minus sign.
  • White noise sounds like it’s repeating every 1.4 seconds
  • Noise is the same in both channels

Frequency generator 200909150

  • Outputs sine, square, triangle, sawtooth
  • Playing more than one sine wave causes clipping, but you can decrease the phone’s volume control
  • Default setting is 440, 444, and 448 Hz, but when played together, the waveform changes abruptly once per second
  • Sine wave THD+N:
    • 40 Hz: 1.00%
    • 440 Hz: 0.056%
    • 10 kHz: 0.051%
    • 20 kHz: 0.222%
  • I don’t know how the square, triangle and sawtooth are generated, but it ain’t right.
    • This is what the “square wave” looks like at 10 kHz:
    • freq gen square 10 kHz
    • And this is the spectrum:
    • frequency generator 10 kHz square
    • Nooot even close

(Using ExtUSB headphone cable, Adobe Audition, Audio Precision.)

Join the Conversation


  1. The 10kHz square will always look bad since the sample rate is only 44.1kHz, there are only just over two samples in a 10kHz signal. After low pass filtering in the DAC it should look like a sine as the next harmonic (the 3rd) is already fully suppressed. To get a better indication of the square wave capability run it at 1kHz.

    I do agree with you that the frequency spectrum doesn’t look right. There should be no sub-harmonics.

  2. I just uploaded my own signal generator app for android. Its called FuncGen, if you want please check it out.

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