Try wrapping the spans in an anchor tag and apply the background image to that.
HTML:
<div class="header">
<a href="/">
<span class="header-title">My gray sea design</span><br />
<span class="header-title-two">A beautiful design</span>
</a>
</div>
CSS:
.header {
border-bottom:1px solid #eaeaea;
}
.header a {
display: block;
background-image: url("./images/embouchure.jpg");
background-repeat: no-repeat;
height:160px;
padding-left:280px;
padding-top:50px;
width:470px;
color: #eaeaea;
}