espeak easy to use C functions

I have been doing some voice stuff and found out that you can make the synthesizer sound much more “real” when you play around with the different pitch and tone rates within the espeak C API. So while doing this I made a small library of functions. Here ya go.
speechFunctions.h

//speechFunctions.h
//these are some speech functions that utilize the espeak C API
//you need to call speakInit at start of program and speakCleanup at the end
//written by: Bill Heaster
//TheCreator a7 ApexLogic |)0T net 

#include <stdio.h>
#include <string.h>
#include <espeak/speak_lib.h>


//don't delete this callback function.
int SynthCallback(short *wav, int numsamples, espeak_EVENT *events)
{

    return 0;
}
int speakInit()
{
 

    //must be called before any other functions
    //espeak initialize
    if(espeak_Initialize(AUDIO_OUTPUT_SYNCH_PLAYBACK,0,NULL,espeakINITIALIZE_PHONEME_EVENTS) <0)
    {
        puts("could not initialize espeak\n");
        return -1;
    }

    espeak_SetSynthCallback(SynthCallback);
    return 0;
}

void speakCleanup()
{
    espeak_Terminate();
}

//takes in a char array and length, will speak the words. 
int speak(char * cp, int len)
{
    espeak_ERROR speakErr;

    if((speakErr=espeak_Synth(cp, len, 0,0,0,espeakCHARS_AUTO,NULL,NULL))!= EE_OK)
    {
        printf("error on synth\n");
        return -1;
    }
    
    
    return 0;
}


//changes the base pitch, accepts values within 0-100
int changePitch(int newVal)
{
    espeak_ERROR sErr;
    
    if(newVal < 0)
    {
        newVal = 0;
    }
    if(newVal > 100)
    {
        newVal = 100;
    }
        
    if((sErr=espeak_SetParameter(espeakPITCH, newVal, 0)) != EE_OK)
    {
        printf("error while setting espeak parameters\n");
        return -1;
    }
    return 0;
}


//changes the range of pitch within the voice accepts values within 0-100, 50 is normal
int changeRange(int newVal)
{
    espeak_ERROR sErr;
    
    if(newVal < 0)
    {
        newVal = 0;
    }
    if(newVal > 100)
    {
        newVal = 100;
    }
    
    if((sErr=espeak_SetParameter(espeakRANGE, newVal, 0)) != EE_OK)
    {
        printf("error while setting espeak parameters\n");
        return -1;
    }
    return 0;
}


//changes word speed values should be bwtween 80 and 450. 
int changeWordSpeed(int newVal)
{
    espeak_ERROR sErr;
    
    if(newVal < 80)
    {
        newVal = 80;
    }
    if(newVal > 450)
    {
        newVal = 450;
    }
        
    if((sErr=espeak_SetParameter(espeakRATE, newVal, 0)) != EE_OK)
    {
        printf("error while setting espeak parameters\n");
        return -1;
    }
    return 0;
}

speechtest.c

//speechtest.c
//Written by: Bill Heaster
//TheCreator a7 ApexLogic |)0T net 

#include <string.h>
#include <stdio.h>
#include "speechSynthesisFunctions.h"

int main(void)
{
    
    char myS[255];
    
    strcpy(myS, "hello world, this is some text  i will be reading to you. what do you think?");
    int len = strlen(myS);
    
    
    speakInit();
    
    speak(myS, len);
    
    changeRange(100);
    
    speak(myS, len);  
    
    changePitch(10);
    
    speak(myS, len);
    
    
    speakCleanup();
    return 0;
}