我正在使用tkinter和google speech to text library用python创建gui语音助手。占位符是文本将来的位置。

我遇到的问题是，在按下麦克风按钮并再次单击它之后，会出现一个错误 RuntimeError: threads can only be started once 即使在听力过程结束之后。
gui类代码：

def __init__(self):
        self.root = Tk()
        self.root.title("HireBot")
        self.root.iconbitmap("icon.ico")
        # To say how big the window should be initially
        self.root.geometry("320x600")  # wxh
        self.root.configure(bg='pink')
        self.logo = ImageTk.PhotoImage(Image.open("icon_deactivated.png"))
        self.logo1 = ImageTk.PhotoImage(Image.open("icon_activated.png"))
        self.l = Label(image=self.logo, borderwidth=0, width=1000, anchor="center", bg="pink")
        self.l.pack()
        self.welcome = Label(text="Welcome! How may I help you today? \n Ask 'what can you do' to know what I can do", borderwidth=0, anchor="center", pady=5, fg="blue", bg="pink", font="arial").pack()
        self.frame = LabelFrame(self.root, padx=5, pady=5)  # pads inside the frame
        self.frame.pack(padx=10, pady=10)  # To pad from the outside
        # To put things in frames
        hold = Label(self.frame, text="Placeholder").pack()
        # Mic button
        self.button_on = ImageTk.PhotoImage(Image.open("MicOn.png").resize((50, 50), Image.ANTIALIAS))
        self.button_off = ImageTk.PhotoImage(Image.open("MicOff.png").resize((50, 50), Image.ANTIALIAS))
        #self.t = Thread(target=self.get_audio, args=("new", None))
        #self.t.setDaemon(True)
        self.mic = Button(self.root, image=self.button_on, border=0, bg="pink", command=threading.Thread(target=self.get_audio).start)
        self.mic.pack()
        self.pressed = True

代码的其余部分

def run(self):
        self.root.mainloop()

    def get_audio(self):

        if self.pressed:
            self.mic.config(image=self.button_off)
            self.pressed = False
            # First create recogniser object
            r = sr.Recognizer()
            # Use microphone to get input
            with sr.Microphone() as source:
                audio = r.listen(source)  # Use speech recogniser to listen to source(microphone)
                # What user said
                said = ""
                try:
                    said = r.recognize_google(audio)  # Uses google API to recognise what user said
                    print(said)
                except Exception as e:
                    print("Exception: " + str(e))
            self.mic.config(image=self.button_on)
            return said
        else:
            self.mic.config(image=self.button_on)
            self.pressed = True
        print(self.pressed)
a = GUI()
a.run()

如何终止线程，以便根据需要多次单击按钮？