Simulate church bell changes ringing. It requires six .wav files representing six bells. They should be less than five seconds long. You might try for bells pitched at C,D,E,G,A,C. The output is written to changes.wav

changes.py

#!/usr/bin/env python3

# Simulate church bell changes ringing. 
# It requires six .wav files representing six bells. 
# They should be less than five seconds long.
# You might try for bells pitched at C,D,E,G,A,C.
#
# The output is written to changes.wav

import random
import wave
import numpy


rate = 22050  

# the sample files: bell-01..06.wav had better be this rate.

bell1=wave.open("bell-01.wav","r")
bell1length = bell1.getnframes()
bell1samples = numpy.fromstring(bell1.readframes(bell1length),dtype=numpy.int16)
bell1samples.resize(rate*5)
bell1.close()

bell2=wave.open("bell-02.wav","r")
bell2length = bell2.getnframes()
bell2samples = numpy.fromstring(bell2.readframes(bell2length),dtype=numpy.int16)
bell2samples.resize(rate*5)
bell2.close()

bell3=wave.open("bell-03.wav","r")
bell3length = bell3.getnframes()
bell3samples = numpy.fromstring(bell3.readframes(bell3length),dtype=numpy.int16)
bell3samples.resize(rate*5)
bell3.close()

bell4=wave.open("bell-04.wav","r")
bell4length = bell4.getnframes()
bell4samples = numpy.fromstring(bell4.readframes(bell4length),dtype=numpy.int16)
bell4samples.resize(rate*5)
bell4.close()

bell5=wave.open("bell-05.wav","r")
bell5length = bell5.getnframes()
bell5samples = numpy.fromstring(bell5.readframes(bell5length),dtype=numpy.int16)
bell5samples.resize(rate*5)
bell5.close()

bell6=wave.open("bell-06.wav","r")
bell6length = bell6.getnframes()
bell6samples = numpy.fromstring(bell6.readframes(bell6length),dtype=numpy.int16)
bell6samples.resize(rate*5)
bell6.close()


pitches = [bell1samples,bell2samples,bell3samples,bell4samples,bell5samples,bell6samples]

changeswav = wave.open("changes.wav","w")
changeswav.setframerate(rate)
changeswav.setsampwidth(2)
changeswav.setnchannels(1)

soundbuffer = numpy.zeros(rate*5,dtype=numpy.int16)

def play(pitch):
    '''pitch is a np array.
    it is added to the soundbuffer (in a dumb way), and then half a second of
    sound is taken off the buffer and written to the output file.
    '''
    global soundbuffer
    soundbuffer = (soundbuffer//2 + pitch//2) #mix the pitch file into the sound
                                              #buffer
    samples = bytes(soundbuffer[:rate//2])  #extract half a second of sound
    changeswav.writeframes(samples)         #and write to output
    soundbuffer = numpy.roll(soundbuffer,-rate//2)
    soundbuffer[-rate//2:] = 0         #roll the soundbuffer and zero the tail

def flush():
    '''Flush the soundbuffer and close'''
    samples = bytes(soundbuffer)
    changeswav.writeframes(samples)
    changeswav.close()
    
    
def playchange(change):
    for bell in change:
        play(pitches[bell])


def randchanges():
    change = [5,4,3,2,1,0]
    while True:
        playchange(change)
        n = random.randint(0,4)
        print(change[n],"to",change[n+1],change)
        change[n],change[n+1]  =  change[n+1],change[n]
        if change == [5,4,3,2,1,0] : break
    playchange(change)
    flush()

def testplay():
    play(fsamples)

def dingdong(changing_pattern):
    change = [5,4,3,2,1,0]
    i=0
    l=len(changing_pattern)
    while True:
        playchange(change)
        n=changing_pattern[i%l]
        print(change[n],"to",change[n+1],change)
        change[n],change[n+1]  =  change[n+1],change[n]
        if change == [5,4,3,2,1,0] : break
        i += 1
    playchange(change)
    flush()

#randchanges()
#dingdong([0,2,4,1,3])
dingdong([0,1,3,4,2])