Can anyone tell me what the spikes are in the screenshot attached. I hear them as little clicks in playback. I tried disconnecting the mic but that doesn’t seem to help. The seem fairly random .

Windows 8
Audacity 2.0.3

Presonus Audiobox

Bob H

To me, it looks like a digital problem (not analog noise). Maybe a driver problem… It could be buffer overflow, although I’m not sure if buffer underflow causes that kind of problem… I think buffer underflow is only audible when you are recording actual sound.

You can try increasing your [u]buffer size[/u], or if you are using a “high resolution” setting, try changing to 16-bit/48kHz.

About buffers & latency -
Computers have been fast-enough for stereo audio recording for many years. But your computer is always multitasking (even if you are running only one application). The digitized audio data-stream flows smoothly into a buffer (“holding tank”) and when the CPU gets around to it, it reads the buffer and sends the data to your hard drive in a quick burst. If the buffer fills-up before CPU gets back to your audio application, you have buffer overflow and you get a glitch.

So, it depends on what (and how much) your operating system is doing in the background. It depends on the size of the buffer. It depends on the amount of audio data (sample rate, bit depth, number of channels). And CPU speed can be a factor if the computer is running multiple applications or something in the background (or the OS) is “hogging” the CPU.

A buffer is also a delay (latency). The bigger the buffer, the more latency you have. For basic recording purposes, this is not an issue and a bigger buffer is better. However, if you are monitoring through the computer (such as a singer monitoring herself/himelf on headphones) latency can be a problem for the performer.

You didn’t actually say you got those ticks while you were recording your microphone. Did you? What kind? How is it connected to the computer? Is it a USB microphone? If there’s enough mystery about what’s happening, it’s time to nail down exactly what you were doing.

Were you overdubbing?


It could be a problem with some kind of physical connection, related to back EMF. An explanation of it is partly at http://www.universalsymbiosis.org on their energy page. The unit hey you flick on a lightswitch can sometimes old TVs will flicker, that kind of thing

I found a loose USB connection from the Presonus to the computer. It forced me to reinstall the Presonus driver and that solved the spike problem.

Bob H