PTB audio problem

After switching to PTB audio as recommended (without it it works fine), some audio won’t play and I get this error:
PTB-ERROR: Audio device 2 has 1 output channels, but provided matrix has non-matching number of 2 columns.
Error in function FillBuffer: Usage error
Number of columns of audio data matrix doesn’t match number of output channels of selected audio device.

My code is:

import os
from psychopy import visual,  core, prefs
prefs.hardware['audioLib'] = ['PTB']
from psychopy import sound

win = visual.Window([1024, 768], monitor=0, units='norm', color='#646464')
slot_machine_ding_sound = sound.Sound(os.path.join(slot_machine_path, 'Sound02 Ding.wav'))
slot_machine_handle_sound = sound.Sound(os.path.join(slot_machine_path, 'Sound03 Handle.wav'))
slot_machine_wheels_sound = sound.Sound(os.path.join(slot_machine_path, 'Sound05 Wheels.wav'))

Any help will be appreciated. thank you !

It looks like you are providing a stereo file but for some reason the sound device will only support mono. Try converting a copy of one of your files from stereo to mono (assuming that doesn’t break some requirement you have), using something like Audacity.

Was that the full error message text?

EDIT: Actually, first you might just want to try forcing the sound to be stereo, rather than allowing it to guess, as follows:

slot_machine_ding_sound = sound.Sound(os.path.join(slot_machine_path, ‘Sound02 Ding.wav’),
                                      stereo = True)

this worked - thank you!!