index.html

## index.html
<!DOCTYPE html>
<meta charset="utf-8">
<title></title>
<style>

body {
  background:#000;
  font: 10px sans-serif;
  width:960px;
  margin:0 auto;
}

.axis path,
.axis line {
  fill: none;
  stroke: #000;
  shape-rendering: crispEdges;
}

.area {
  fill: black;
}

.line {
  stroke-width:2;
  stroke:#eee;
}

</style>
<body>
<script src="http://d3js.org/d3.v3.js"></script>
<script>

var margin = {top: 20, right: 20, bottom: 30, left: 50},
    width = 960 - margin.left - margin.right,
    height = 500 - margin.top - margin.bottom;

var x = d3.time.scale()
    .domain([0, 1])
    .range([0, width]);

var y = d3.scale.linear()
    .domain([0, 1])
    .range([height, 0]);

var area = d3.svg.area()
    .x(function(d) { return x(d.x); })
    .y0(height)
    .y1(function(d) { return y(d.y); })
    .interpolate('basis');

var line = d3.svg.line()
    .x(function(d) { return x(d.x); })
    .y(function(d) { return y(d.y); })
    .interpolate('basis');

var svg = d3.select("body").append("svg")
    .attr("width", width + margin.left + margin.right)
    .attr("height", height + margin.top + margin.bottom)
  .append("g")
    .attr("transform", "translate(" + margin.left + "," + margin.top + ")");

var data = d3.range(0, 18).map(function(y) {
    return d3.range(0, 40).map(function(x) {
        return {
            x: x / 40,
            y0: y / 20,
            y: (y / 20) + Math.sin(x / (Math.PI * 4)) * (Math.random() / 10)
        };
    });
}).reverse();

function draw(data) {

    var wave = svg.selectAll('g.wave')
        .data(data)
        .enter()
        .append('g')
        .attr('class', 'wave');

    wave.append('path')
        .attr("class", "area")
        .attr("d", area);

    svg.selectAll('path.area').transition().duration(100).attr("d", area);

    wave.append('path')
        .attr("class", "line");

    svg.selectAll('path.line').transition().duration(1000).attr("d", line);

}

window.setInterval(function() {
    for (var y = 0; y < data.length; y++) {
        for (var x = 0; x < data[y].length; x++) {
            data[y][x].y = Math.min(
                data[y][x].y0 + 0.09,
                Math.max(
                    data[y][x].y0 - 0.09, data[y][x].y + (Math.random() - 0.5) * Math.sin(x / (Math.PI * 4)) * 0.02));
        }
    }
    draw(data);
}, 1000);

draw(data);

</script>