问语音识别：一句话识别报错，求助？

"""
    功能：调用腾讯语音识别的一句话识别接口
    版本：1.0
    日期：2018-12-5
    说明：安装腾讯最新的sdk后，直接调用
"""
from tencentcloud.common.credential import Credential
from tencentcloud.aai.v20180522.aai_client import AaiClient
from tencentcloud.aai.v20180522.models import SentenceRecognitionRequest
import base64
import json
import sys

with open(r'.\831800004885046-00-u.wav', 'rb') as f:
    file = f.read()

speech_base64 = base64.b64encode(file).decode('utf-8')
speech_length = len(file)
print(speech_length)
# 用户需修改为自己官网的appid，secretid与sectretkey
secretkey = 'IZjjesvmYSQEvTpzbDNXfVRDtOo6KqcJ'
secretid = 'AKIDUt3dzJG3wqmZEz6AXkyf5SkeTH0zhm5M'
appid = 1258179684
# 实例化认证对象，入参需要传入ID和KEY
# 就是鉴权
cred = Credential(secretId=secretid, secretKey=secretkey)

# 实例化产品
client = AaiClient(cred, "ap-chongqing")

# 实例化请求对象
param = {
    'ProjectId':appid,
    'SubServiceType':2,
    'EngSerViceType':'16k',
    'SourceType':1,
    'VoiceFormat':'wav',
    'UsrAudioKey':'shui3qing1shan1lan2',
    'Data':speech_base64,
    'DataLen':speech_length
}
req = SentenceRecognitionRequest()
req.from_json_string(json.dumps(param).encode('utf-8'))
# print(type(json.dumps(param).encode('utf-8')))
# print(sys.getsizeof(json.dumps(param).encode('utf-8')))
# 通过client对象调用访问接口，需要传入请求对象
response = client.SentenceRecognition(req)

# 输出返回信息
print(response.to_json_string())
print(type(response))