Hi. Here is the source code. Teensy 3.5.
Basic servo test sketch (not included here) does work. Also note that I have a mosfet switch before the servo which is known to be working (indicator LED)
The serial monitor produces good results for what I am trying to do.

Sonar, audio, mosfet, and serial monitor numbers are all dandy. The servo does nothing at all.

I have tried messing with the sample time, its not that either.

Must be a line of code. Can you help?

Thank you!! SirEdward
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#include <Audio.h>
#include <Wire.h>
#include <SPI.h>
#include <SD.h>
#include <SerialFlash.h>
#include <Servo.h>

// Configuration
// Connections
#define SERVO_PIN 10 // Jaw servo
#define PING_PIN 5 // ping / echo for sonar distance sensor
#define ECHO_PIN 6
#define MOSFETPin 9 // mostfet for servo power control

// How long until the ping returns to consider it a "trigger"
#define SONAR_THRESHOLD 900 // microseconds.
// Speed of sound in air is about 343 m/s, so this is about 15 cm (~6 in), or a 30cm round trip.
// Quick calculators:
// const SONAR_THRESHOLD (148 * 6) // ~inches
// const SONAR_THRESHOLD (58 * 15) // ~cm

// Servo range configuration
#define JAW_OPEN 70
#define JAW_CLOSED 0

// Length of time for `loop()` to run. 1000/25 Hz (40ms) should be pretty fluid
#define SAMPLE_TIME 300 // ms

// Sound file to play when sonar triggers
#define SAMPLE_FILE "01.wav"

// Delay playback to compensate for the jaw servo's lag.
#define SERVO_DELAY 50 // ms

// To play with this, import the below block into https://www.pjrc.com/teensy/gui/

// playSdWav1 will use the built-in sd card slot, assumed to have a fat32 filesystem.
// If you're using some other way to attach SD, or you'd like to use in-memory or
// whatever, there are other options.

#include <Audio.h>
#include <Wire.h>
#include <SPI.h>
#include <SD.h>
#include <SerialFlash.h>

// GUItool: begin automatically generated code
AudioPlaySdWav playSdWav1; //xy=329,371
AudioMixer4 mixer1; //xy=548,386
AudioEffectDelay delay1; //xy=749,424
AudioOutputAnalog dac1; //xy=951,421
AudioAnalyzePeak peak1; //xy=973,360
AudioConnection patchCord1(playSdWav1, 0, mixer1, 0);
AudioConnection patchCord2(playSdWav1, 1, mixer1, 1);
AudioConnection patchCord3(mixer1, delay1);
AudioConnection patchCord4(delay1, 0, peak1, 0);
AudioConnection patchCord5(delay1, 1, dac1, 0);
// GUItool: end automatically generated code

#define SDCARD_CS_PIN BUILTIN_SDCARD
#define SDCARD_MOSI_PIN 11 // not actually used
#define SDCARD_SCK_PIN 13

Servo jaw;

// Entirely optional. For stable sample management. `elapsedMillis` is a teensy type that
// automatically counts up, so it's useful for making sure if you want 25Hz, you _get_ 25Hz.
elapsedMillis timing;

int ping() {
digitalWrite(PING_PIN, LOW);
delayMicroseconds(2);
digitalWrite(PING_PIN, HIGH);
delayMicroseconds(10);
digitalWrite(PING_PIN, LOW);
if (pulseIn(ECHO_PIN, HIGH, SONAR_THRESHOLD) != 0) {
return HIGH;
}
return LOW;
}


uint8_t mosfet_state = LOW;
void set_mosfet(uint8_t state) {
if (state != mosfet_state) {
Serial.print("Setting MOSFET to ");
Serial.println(state == LOW ? "LOW" : "HIGH");
mosfet_state = state;
digitalWrite(MOSFETPin, mosfet_state);
}
}


void setup() {
Serial.begin(9600);
Serial.println("initializing audio memory");

// Set up audio memory. You need at least 1 block for each 2.9 ms of delay, plus
// a minimum of 8 blocks for the player.
AudioMemory((int) (ceil(SERVO_DELAY / 2.9) + 8));
Serial.println("initializing pins");
jaw.attach(SERVO_PIN);
pinMode(PING_PIN, OUTPUT);
pinMode(ECHO_PIN, INPUT);
pinMode(MOSFETPin, OUTPUT);
delay1.delay(0, 0);
delay1.delay(1, SERVO_DELAY);
delay1.disable(2);
delay1.disable(3);
delay1.disable(4);
delay1.disable(5);
delay1.disable(6);
delay1.disable(7);

mixer1.gain(0, 1.0);
mixer1.gain(1, 1.0);
mixer1.gain(2, 0);
mixer1.gain(3, 0);

Serial.println("initializing SD access");
SPI.setMOSI(SDCARD_MOSI_PIN);
SPI.setSCK(SDCARD_SCK_PIN);
if (!(SD.begin(SDCARD_CS_PIN))) {
// stop here, but print a message repetitively
while (1) {
Serial.println(SD.begin(SDCARD_CS_PIN));
Serial.println("Unable to access the SD card");
delay(500);
}
}
}

void loop_state_waiting() {
if (mosfet_state == HIGH) {
Serial.println("playback ended; returning to sleep.");
}
set_mosfet(LOW);
if (ping() == HIGH) {
Serial.println("sonar ping! Starting sound/animation.");
set_mosfet(HIGH);
playSdWav1.play(SAMPLE_FILE);
delay(5);
}
}

void loop_state_playing() {
if (peak1.available()) {
float level = peak1.readPeakToPeak();
int new_servo_pos = (int) (level * (JAW_OPEN - JAW_CLOSED) / 2.0 + JAW_CLOSED);
Serial.print("Level: ");
Serial.print(level);
Serial.print("; servo: ");
Serial.println(new_servo_pos);
jaw.write(new_servo_pos);
}
}

void loop() {
// resets the counter
timing = 0;
if (!playSdWav1.isPlaying()) {
loop_state_waiting();
} else {
loop_state_playing();
}
// Only delay for the remaining time in the sample.
delay(SAMPLE_TIME - timing);
}