<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def preproc(path, sr=16000, alpha=0.95):
 """Preprocess a .wav file for later processing. Currently assumes a 16-bit PCM input. Only returns left channel of stereo files. Parameters path : str Full path to .wav file to load. sr : int, optional Sampling rate to resample at, if specified. alpha : float, optional Alpha for preemphasis, defaults to 0.97. Returns ------- int Sampling rate. array Processed PCM. """

    oldsr, sig = wavfile.read(path)

    try:
        sig = sig[:, 0]
    except IndexError:
        pass

    if False and sr != oldsr:
        t = len(sig) / oldsr
        numsamp = int(t * sr)
        proc = resample(sig, numsamp)
    else:
        proc = sig
        sr = oldsr
    # proc = proc / 32768
    if alpha is not None and alpha != 0:
        proc = lfilter([1., -alpha], 1, proc)
    return sr, proc