Obtain audio information from mic and play in MATLAB
Input:
Your signal looks like it doesn't have much dynamic range.
You may want to look into amplifying it before it reaches the arduino's ADC.
The AVR based Arduinos have a 10 bit ADC -- 0 to 1024.
At 5 volts Vref that is
\$ \frac{5volts}{ 1024 counts} = 4.9 \frac{mVolt }{ count}\$
Your signal ranges from ~150 to ~225. This is 75 counts of range or 7% of the ADC's resolution. Your input signal varies by about 366mV peak to peak.
It should vary by about 2.5v peak to peak.
Output:
Matlab's documentation on audio files states the following:

The MATLAB sound and soundsc functions support only single- or double-precision values between -1 and 1.

Your arduino code is printing values from 0-1024. Integers.
You will need to normalize them and remove the DC bias: make the signal have an average of 0, and a range of [-1 1].
input = double(csvread('samples.csv'));
input = input - 512; % convert the [0 to 1024] range to [-512 to 512]
input = input ./ 512; % convert the [-512 to 512] range to [-1 to 1]
sound(input, 8192);