Clean recorded audio with Audacity

When you’ve finished recording: –

Ctrl A to select all, Effect – Normalize (this’ll adjust the waveform so that it’s a consistent volume)
– Select ONLY the beginning, before you begin speaking: Effect – Noise Reduction – Get Noise Profile – OK

Ctrl A to select all again Effect – Noise Reduction – OK. Normalize it again until your audio sounds clear. Repeat if necessary.