How is binary data related to double precision data?
I don't know much about Matlab's wavread, but double precision is a standard for describing a &quot;floating point&quot; value. That is, a value that always has the same number of (binary) digits of precision.
A double precision floating point number in binary looks like this: 
Each of those boxes represents a bit (short for &quot;binary digit&quot;, or a 1 or a 0). It works like scientific notation: the exponent and fraction are both base-2 representations of numbers, and the number this represents is (with some exceptions for things like 0 and NaN) $$(-1)^{\text{sign}}\times 2^{\text{exponent - exponent bias}} \times 1.\text{fraction}$$
Where the &quot;exponent bias&quot; is there to allow you to represent negative exponents, and the &quot;.&quot; in $1.\text{fraction}$ is a &quot;binary point&quot; instead of a decimal point.
You can read about the particulars of the double precision format here, which is where I got the image and formula.