如何生成不同频率的连续音？

import numpy as np
from scipy.io.wavfile import write

def generate_tone(freq, duration, volume=0.1):
    sample_rate = 44100
    t = np.linspace(0, duration, int(duration * sample_rate), False)
    tone = np.sin(freq * t * 2 * np.pi)
    audio = (volume * tone).astype(np.int16)
    return audio

from simpleaudio import play_buffer

freq1 = 440  # 440 Hz
freq2 = 880  # 880 Hz
duration = 1  # 1 second

tone1 = generate_tone(freq1, duration)
tone2 = generate_tone(freq2, duration)

play_buffer(tone1, 1, 2, 44100).wait_done()
play_buffer(tone2, 1, 2, 44100).wait_done()

write('tone1.wav', 44100, tone1)
write('tone2.wav', 44100, tone2)