问为什么 我的音频不能被解析？

<?php

require('./include.php');

//请在此填入AppID与AppKey
$app_id = '2110386293';
$app_key = '7kywTjWd30fl51dZ';

//设置AppID与AppKey
Configer::setAppInfo($app_id, $app_key);

// 自定义分片规则和是否返回中间结果
// $speech_data = file_get_contents("php://input");
// file_put_contents("wavs/" . uniqid() . '.wav', $speech_data);

$speech_data = file_get_contents("./wavs/5c237f9ed6815.wav");

$chunk_size  = 4096; //每个分片4096Byte
$total_chunk = ceil(strlen($speech_data) / $chunk_size);
$params = array(
    'format'    => 2,
    'rate'      => 8000,
    'bits'      => 8,
    'cont_res'  => 1,
    'speech_id' => "{$app_id}_" . md5(time()),
);

$content = "";
for ($i = 0; $i < $total_chunk; ++$i)
{
    $chunk_data = substr($speech_data, $i * $chunk_size, $chunk_size);
    $params['speech_chunk'] = base64_encode($chunk_data);
    $params['len']          = strlen($chunk_data);
    $params['seq']          = $i * $chunk_size;
    $params['end']          = ($i == ($total_chunk-1)) ? 1 : 0;
    $result = API::wxasrs_perchunk($params);

    // 处理数据
    $response = json_decode($result);
    if ($response->ret != 0) {
        var_dump($response);
        continue;
    }
    if (isset($response->data->speech_text)) {
        $content .= $response->data->speech_text;
    }
}

// 识别后落入日志中
if (empty($content)) {
    die();
}
$stream = fopen("log.txt", "a+");
$size = strlen($speech_data);
fwrite($stream, "[{$size}] {$content} \r\n");