javascripts + html5 ЗМЕЙКА Как изменить скорость змейки?

Нужно как то сделать чтоб менялась скорость змейки при сьедании яблока, помогите реализовать пожалуйста!

const canvas = document.getElementById("game");
const ctx = canvas.getContext("2d");

const ground = new Image();
ground.src = "img/ground.png";

const foodImg = new Image();
foodImg.src = "img/apple.png";

const suchImg = new Image();
suchImg.src = "img/such1.png";


let box = 32;

let score = 0;

let speeds  = {
   37: 1,
   38: 10,
   39: 15,
   40: 25
};

  let food = {
     x: Math.floor((Math.random() * 12 + 1)) * box,
     y: Math.floor((Math.random() * 10 + 3)) * box,
  };

  let snake = [];
  snake[0] = {
     x: 12 * box,
     y: 10 * box
  };

  document.addEventListener("keydown", direction);

  let dir;

  function direction(event) {
    if(event.keyCode == 37 && dir != "right")
      dir = "left";
    else if(event.keyCode == 38 && dir != "down")
      dir = "up";
   else if(event.keyCode == 39 && dir != "left")
      dir = "right";
   else if(event.keyCode == 40 && dir != "up")
      dir = "down";
  }



 function eatTail(head, arr) {
   for(let i = 0; i < arr.length; i++) {
   if(head.x == arr[i].x && head.y == arr[i].y)
   clearInterval(game);
   }
  }

  function drawGame() {
  ctx.drawImage(ground, 0, 0);

  ctx.drawImage(foodImg, food.x, food.y);

  for(let i = 0; i < snake.length; i++) {


  ctx.drawImage(suchImg, snake[i].x, snake[i].y, box , box);

  }

  ctx.fillStyle = "red";
  ctx.font = "50px Arial";
  ctx.fillText(score, box * 2.7, box * 1.9);

  let snakeX = snake[0].x;
  let snakeY = snake[0].y;

  if(snakeX == food.x && snakeY == food.y) {
  score++;
  food = {
  x: Math.floor((Math.random() * 17 + 1)) * box,
  y: Math.floor((Math.random() * 15 + 3)) * box,
  };
  } else {
  snake.pop();
  }

  if(snakeX < box || snakeX > box * 17
  || snakeY < 3 * box || snakeY > box * 17)
  clearInterval(game);

  if(dir == "left") snakeX -= box;
  if(dir == "right") snakeX += box;
  if(dir == "up") snakeY -= box;
  if(dir == "down") snakeY += box;


 let newHead = {
 x: snakeX,
 y: snakeY
 };



eatTail(newHead, snake);

snake.unshift(newHead);
}

let game = setInterval(drawGame, 100);