audio streaming not working in flask using generator / yield

I am trying to stream two audio files one after the other in flask using generator / yield. However it plays only the first file and not the other. Following is my code:

from flask import Flask, send_file, Response
import random
import time
import wave

# Flask constructor takes the name of
# current module (__name__) as argument.
app = Flask(__name__)
 
# The route() function of the Flask class is a decorator,
# which tells the application which URL should call
# the associated function.
@app.route('/')
# ‘/’ URL is bound with paadas() function.
def paadas():
    Approach 2: not working
    def generate(files):
        for file in files:
            yield file.read()

    files = []
    number = random.randint(1,10)
    f1 = open("../numbers/" + str(number) + ".wav", 'rb')
    files.append(f1)
    times = random.randint(1,10)
    f2 = open("../times/" + str(times) + ".wav", 'rb')
    files.append(f2)
    return Response(generate(files), mimetype='audio/wav')

# main driver function
if __name__ == '__main__':
 
    # run() method of Flask class runs the application
    # on the local development server.
    app.run()

What am I missing here? You can see my attempt of three approaches at https://github.com/sameermahajan/PaadasMLFlaskApp Only the first one works but it is not very elegant. If you want to try out the program, you can get the prerecorded audios of "numbers" and "times" from https://github.com/sameermahajan/Paadas These are numbers in marathi (an Indian language) in reciting table format.

When streaming, the headers from the second file are not properly interpreted it might cause the second file not to play.

We could use the wave module to remove the headers from the second file and then concatenate the audio files, notice that it might not work if the file does not have the same sample rate, sample width, and number of channels.

from flask import Flask, Response
import random
import wave
import io

app = Flask(__name__)

@app.route('/')
def paadas():
    def generate(files):
        with wave.open(files[0], 'rb') as f:
            params = f.getparams()
            frames = f.readframes(f.getnframes())
        
        for file in files[1:]:
            with wave.open(file, 'rb') as f:
                frames += f.readframes(f.getnframes())
        
        buffer = io.BytesIO()
        with wave.open(buffer, 'wb') as f:
            f.setparams(params)
            f.writeframes(frames)
        
        buffer.seek(0)
        return buffer.read()

    files = []
    number = random.randint(1,10)
    files.append("../numbers/" + str(number) + ".wav")
    times = random.randint(1,10)
    files.append("../times/" + str(times) + ".wav")
    
    return Response(generate(files), mimetype='audio/wav')

if __name__ == '__main__':
    app.run()