CREATE EXTENSION "soundex-type";
CREATE TABLE test_table (
  id INT,
  data soundex
);
INSERT INTO test_table VALUES (1, 'hello');
INSERT INTO test_table VALUES (2, 'world');
INSERT INTO test_table VALUES (3, 'john');
INSERT INTO test_table VALUES (4, 'joan');
SELECT * FROM test_table;
 id | data 
----+------
  1 | H400
  2 | W643
  3 | J500
  4 | J500
(4 rows)

DROP TABLE test_table;