Sine Wave spectrum showing multiple frequencies - Audacity I am generating a sine wave using audacity
with 2000 Hz, 30s duration, amplitude 0.5

48 kHz is the sampling rate of the recording device.

I just play and record the generated sound, this is the spectrogram that I get. (Top is original while bottom is recorded) Frequencies other than 2kHz are also showing up in the spectrogram with significant power density. (Using 2048 point hanning window for FFT).



This is the time domain representation for the generated and recorded signal, this is shown to ensure clipping is not happening.


Why does the spectrogram show these higher frequencies and how could I remove them.

I could not find answer to my query on other similar posts in DSP stack exchange thus am creating this post.
Following could be the reason for extra frequencies - 


Non Ideal characteristics of speaker used to play the generated sine wave.
Non Ideal characteristics of microphones used to record the played sine wave.


Also one needs to make sure that given sampling rate(48kHz) is supported by the speaker/sound card and the recording microphone otherwise extra frequency components will be introduced.