Audio played way too fast, although the format is right.

[vohai2003]

Hi.
I'm trying to make a bot that play audio generated from scipy. I double-checked the format and nothing wrong there (16-bit PCM, 48000 Hz sampling rate; checked with Audacity). But then when I played the audio, it's played way too fast, just like when I play a 44100 Hz PCM audio.
Can you suggest me a solution?
My tone generator code:

import math
import numpy as np
from scipy.io.wavfile import write
def FSK(message:str):
    sampling_rate = 48000
    baud_rate = 128
    samples_per_bit = 1.0 / baud_rate * sampling_rate
    message = "KAKAKAKAKAKAKAKAKAKAKAKAKAKAKAKAKAKAKAKAKA"+message+"KNKNKNKNKNKNKNKNKNKNKNKNKNKNKNKNKNKNKNKN"
    content = []
    i = -1
    for char in message:
        i += 1
        encoded = char.encode("utf-8").hex()
        binencoded = bin(int(encoded,16))[2:].zfill(24)
        print(binencoded)
        for flip in binencoded:
            if flip == "0":
                tone = 640
            elif flip == "1":
                tone = 1024
            content.append(tone)
    bit_arr = np.array(content)
    symbols_freqs = np.repeat(bit_arr, samples_per_bit)
    delta_phi = symbols_freqs * np.pi / (sampling_rate / 2.0)
    phi = np.cumsum(delta_phi)
    signal = np.sin(phi)
    signal *= np.iinfo(np.int16).max*0.4
    print(signal.max())
    write("FSK.wav", 48000, signal.astype(np.int16))